JP2000257479A - Catalyst warm-up control unit for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly raise temperature of catalysts during a starting process and fully satisfy exhaust gas regulations. SOLUTION: A catalyst warm-up control unit comprises a means to obtain information, corresponding to a temperature of catalysts mounted in an exhaust pipe of an internal combustion engine as a catalyst temperature TC, various sensors for detecting the operating conditions of the internal combustion engine, and a means for controlling the air-fuel ratios for the internal combustion engine depending on its operating conditions. The catalyst warm-up control unit further comprises an air-fuel ratio shift-to-lean means S3 to compensate a target air-fuel ratio A/Fo to a lean side to promote activation of the catalyst, when the catalyst temperature is lower than a prescribed temperature corresponding to a catalyst activation temperature. The various sensors detect at least air intake information and crank angle information. When a catalyst temperature is below the prescribed temperature, the air-fuel ratio shift-to-lean means adjusts the target air-fuel ratio to a reactive lean air-fuel ratio, which is higher than both of a normal air-fuel ratio A/Fn and theoretical air-fuel ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst temperature raising control device for a spark ignition type internal combustion engine which complies with exhaust gas regulation, and more particularly to a catalyst temperature raising device for an internal combustion engine capable of rapidly raising a catalyst temperature to an activation temperature. The present invention relates to a temperature control device.

[0002]

2. Description of the Related Art Conventionally, an exhaust pipe of an internal combustion engine is provided with a catalyst for purifying exhaust gas. But,
Since the catalyst functions at an active temperature, when the internal combustion engine is in a cold state, it is necessary to increase the catalyst temperature by, for example, hot exhaust gas.

Therefore, in a conventional catalyst temperature rise control device for an internal combustion engine, in order to promote a rise in the catalyst temperature at the time of starting, for example, a technique of, for example, retarding the ignition timing has been proposed.

For example, in an exhaust gas purifying apparatus described in Japanese Utility Model Laid-Open Publication No. 51-79212, heated secondary air is introduced into an intake system, and ignition timing is corrected for retardation so that the starting time is reduced. Quickly raises the catalyst temperature.

FIG. 38 is a block diagram showing a conventional catalyst temperature rise control device for an internal combustion engine. FIG. 39 is an explanatory diagram showing a change in the purification rate of exhaust gas with respect to the catalyst temperature TC. The horizontal axis represents the catalyst temperature TC, and the vertical axis represents the purification rate [%].

In FIG. 39, the solid line is a purification rate for CO (carbon monoxide) and HC (hydrocarbon), and the dashed line is N
It shows the purification rate for Ox (nitrogen oxide). When the catalyst temperature TC rises, the purification rate becomes the activation start temperature (= 130
° C), the temperature starts to rise from 0%, and reaches a maximum value (= 98%) when the temperature reaches the full activation temperature (= 180 ° C).

In FIG. 38, an engine 1 constituting a main body of an internal combustion engine has an intake pipe 2 for introducing air into the engine 1, and an exhaust pipe 3 for discharging exhaust gas burned in the engine 1. Are provided.

An air cleaner 4 is provided upstream of the intake pipe 2.
The air flow sensor 5 that detects the intake air amount Qa of the engine 1 is provided downstream of the air cleaner 4.

A throttle valve 6 for adjusting the amount of intake air Qa is provided in the intake pipe 2 downstream of the air flow sensor 5.

Further, a bypass passage 7 for bypassing the throttle valve 6 and an idle speed control valve (hereinafter referred to as I) for adjusting the opening of the bypass passage 7 are provided in the intake pipe 2.
8 (referred to as SC valve).

The ISC valve 8 adjusts a bypass intake air amount that flows by bypassing the throttle valve 6, and
Is controlled to a target value. In the exhaust pipe 3,
An air-fuel ratio sensor 9 for detecting the oxygen concentration in the exhaust gas as an air-fuel ratio A / F is provided.

Further, downstream of the exhaust pipe 3, catalysts 10 and 11 for purifying exhaust gas by a chemical reaction are provided. One catalyst 10 is provided directly below the exhaust pipe 3, and the other catalyst 11 is provided below the floor of the exhaust pipe 3. Generally, the catalysts 10, 11 are called three-way catalysts, and oxidize CO and HC, reduce NOx, and remove harmful components in exhaust gas.

An injector 12 for injecting fuel sent from a fuel pump (not shown) is provided at an intake portion corresponding to each cylinder of the engine 1. Also,
The engine 1 is provided with a crank angle sensor 13 that outputs a crank angle signal CA corresponding to the engine speed Ne.

An electronic control unit (hereinafter, referred to as an ECU) 14 including a microcomputer is provided with an engine based on operating state information (intake amount Qa, air-fuel ratio A / F, crank angle signal CA, etc.) input from each sensor. 1 to calculate a fuel injection signal J for driving the injector 12, an ISC control signal C for driving the ISC valve 8, and an ignition signal P for driving an ignition device (described later). Output.

Although not shown here, generally, various sensors for detecting the operating state of the engine 1 include a water temperature sensor for detecting a cooling water temperature TW of the engine 1 and an intake air temperature for detecting a temperature of intake air. A sensor or the like is provided.

The ignition device is responsive to an ignition signal P, an ignition plug (not shown) provided in each cylinder of the engine 1, an ignition coil 15 connected to a battery and applying a high voltage to the ignition plug. And an igniter 16 for shutting off the power supply to the ignition coil 15.

Next, the operation of the conventional catalyst temperature rise control device for an internal combustion engine shown in FIG. 38 will be described. First, the injector 12 injects a required amount of fuel into the engine 1 according to the drive pulse width of the fuel injection signal J. In addition, the igniter 16 cuts off the power supply to the ignition coil 15 in response to the ignition signal P, applies a high voltage to the ignition plug, and ignites the air-fuel mixture in the cylinder.

At this time, the amount of fuel injected from the injector 12 is calculated according to the intake air amount Qa and the engine speed Ne, and is corrected based on the air-fuel ratio A / F. The ignition timing is set based on the intake air amount Qa and the engine speed Ne.

Further, as is well known, the fuel injection timing and the ignition timing are calculated using the pulse edge (reference crank angle position) of the crank angle signal CA as a timer control reference.

The air-fuel mixture burned in the engine 1 is
Exhaust gas is exhausted from the exhaust pipe 3, but the catalyst 1
Purified through 0, 11 to remove harmful components. The operating temperature range of the catalysts 10 and 11 is usually from 130 ° C.
It is about 900 ° C.

Here, when raising the temperature of the catalysts 10 and 11 quickly, as described in the above-mentioned known literature,
The ignition signal P based on the normal operation is corrected to correct the target ignition timing to the retard side.

Due to such a retard correction of the ignition timing, the high-temperature exhaust gas immediately after the combustion (or during the combustion) is discharged from the exhaust pipe 3.
, The temperature of the catalysts 10, 11 rises rapidly from the cooler temperature to the activation temperature.

On the other hand, in the idling operation state, the throttle valve 6 is fully closed and the vehicle stops.
The idle speed is controlled by adjusting the opening of the ISC valve 8.

That is, during idling, the ECU 1
4 calculates the bypass intake air amount for obtaining the target idle speed, outputs the ISC control signal C, and corrects the ISC control signal C based on the deviation between the actual engine speed Ne and the target idle speed. Then, feedback control is performed on the bypass intake air amount (the opening degree of the ISC valve 8).

In the cold state of the engine 1,
Set the target idle speed to a predetermined amount (100 rpm to 200 rpm).
pm) to allow the engine 1 to stably burn.

However, in recent years, LEV (Low Em)
As referred to as the “issue vehicle”, exhaust gas regulations are being tightened, and in order to respond to this, it is necessary to raise the catalyst temperature to the activation temperature more quickly. Further, when realizing early activation of the catalyst, it is also required to avoid occurrence of adverse effects such as deterioration of fuel efficiency and drivability.

[0027]

As described above, the conventional catalyst temperature rise control device for an internal combustion engine corrects the ignition timing by retarding, for example, but cannot raise the catalyst temperature sufficiently quickly. Therefore, there has been a problem that exhaust gas cannot be purified to a degree that sufficiently satisfies exhaust gas regulations at the time of starting or idling.

The present invention has been made in order to solve the above-mentioned problems. The present invention has been made to make the air-fuel ratio lean, or to increase the idle speed further than at the time of normal increase correction (at the time of normal control). An object of the present invention is to provide a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy the exhaust gas regulation by rapidly raising the catalyst temperature even at the time of startup or idle operation.

[0029]

A catalyst temperature rise control device for an internal combustion engine according to the present invention includes a catalyst comprising a three-way converter provided in an exhaust pipe of the internal combustion engine, and information corresponding to the temperature of the catalyst. Catalyst temperature obtaining means for obtaining as, various sensors for detecting the operating state of the internal combustion engine, air-fuel ratio control means for controlling the air-fuel ratio of the internal combustion engine according to the operating state, Air-fuel ratio leaning means for correcting the target air-fuel ratio of the internal combustion engine to a lean side in order to promote the activation of the catalyst when the temperature is lower than the corresponding predetermined temperature. , And crank angle information corresponding to the rotational speed of the internal combustion engine, and the air-fuel ratio leaning means detects
When the catalyst temperature is lower than the predetermined temperature, the target air-fuel ratio is
The activation lean air-fuel ratio is set higher than the air-fuel ratio during normal control and higher than the stoichiometric air-fuel ratio.

Further, the air-fuel ratio leaning means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes: first comparing means for comparing the catalyst temperature with a first predetermined temperature near the activation temperature; A second comparing means for comparing the temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, wherein the catalyst temperature is different from the first predetermined temperature and the second predetermined temperature. If it is within the range, the target air-fuel ratio is set to the activation lean air-fuel ratio.

Further, the air-fuel ratio leaning means of the catalyst temperature raising control device for an internal combustion engine according to the present invention includes tailing means for gradually changing the target air-fuel ratio at the time of switching control of the target air-fuel ratio. When the catalyst temperature is equal to or higher than the first predetermined temperature, the target air-fuel ratio is gradually increased by a constant value from the air-fuel ratio during the normal control to the activated lean air-fuel ratio, and the catalyst temperature becomes higher than the second predetermined temperature. When the target air-fuel ratio is also high, the target air-fuel ratio is gradually reduced by a constant value from the activated lean air-fuel ratio to the air-fuel ratio during normal control.

Further, the catalyst temperature acquiring means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature.

The catalyst temperature acquiring means of the internal combustion engine catalyst temperature rise control device according to the present invention includes an exhaust temperature sensor provided in an exhaust pipe of the internal combustion engine for detecting an exhaust temperature, and a catalyst temperature based on the exhaust temperature. And estimating means for estimating the catalyst temperature.

Further, the catalyst temperature acquiring means of the internal combustion engine catalyst temperature rise control device according to the present invention includes catalyst temperature estimating means for estimating and calculating the catalyst temperature based on at least the intake air amount information of the internal combustion engine.

The catalyst temperature estimating means of the internal combustion engine catalyst temperature rise control device according to the present invention includes initial temperature estimating means for estimating and calculating the initial temperature of the catalyst. This is for estimating and calculating the initial temperature of the catalyst based on the hourly water temperature and the start-up intake air temperature.

Further, the initial temperature estimating means of the catalyst temperature raising control device for an internal combustion engine according to the present invention estimates the starting water temperature as the initial catalyst temperature when the starting water temperature and the starting intake air temperature are substantially equal. If the starting water temperature and the starting intake air temperature are different, the initial temperature of the catalyst is estimated and calculated based on the difference between the starting water temperature and the starting intake air temperature.

The catalyst temperature estimating means of the internal combustion engine catalyst temperature increasing control device according to the present invention sets the water temperature at the start of the internal combustion engine as the initial catalyst temperature, and calculates the generated heat amount calculated from the intake air amount information. The catalyst temperature is estimated and calculated based on the heat capacity of the exhaust system including the exhaust pipe.

The predetermined temperature in the internal combustion engine catalyst temperature raising control apparatus according to the present invention is set to a value obtained by adding a predetermined margin temperature to the catalyst activation temperature.

The predetermined temperature in the catalyst temperature raising control device for an internal combustion engine according to the present invention is set to a value obtained by subtracting a predetermined margin temperature from the activation temperature of the catalyst.

Further, the catalyst temperature rise control device for an internal combustion engine according to the present invention is for obtaining, as a catalyst temperature, a catalyst comprising a three-way converter provided in an exhaust pipe of the internal combustion engine, and information corresponding to the temperature of the catalyst. Catalyst temperature acquisition means, various sensors for detecting the operating state of the internal combustion engine, idle control means for controlling the idle speed of the internal combustion engine in accordance with the operating state, and a predetermined temperature corresponding to the catalyst temperature corresponding to the activation temperature of the catalyst. Idle speed increasing means for correcting the target idle speed of the internal combustion engine to a higher speed than the idle speed during normal control in order to promote activation of the catalyst when the engine speed is lower than the idle speed. When the catalyst temperature is lower than the predetermined temperature, the raising means adjusts the target idle rotation speed for a predetermined period until the catalyst temperature reaches the activation temperature. Remote it is for setting the high activation increased engine speed.

Further, the idle speed increasing means of the catalyst temperature increasing control device for the internal combustion engine according to the present invention comprises: first comparing means for comparing the catalyst temperature with a first predetermined temperature lower than the activation temperature; And a second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, wherein the catalyst temperature is between the first predetermined temperature and the second predetermined temperature. If it is within the range, the target idle speed is set to the activation rise speed.

Further, the idle speed increasing means of the catalyst temperature raising control device for the internal combustion engine according to the present invention includes tailing means for gradually changing the target idle speed during the switching control of the target idle speed. When the catalyst temperature is equal to or higher than the first predetermined temperature, the target gradually increases the target idle speed by a constant value from the idle speed during normal control to the activation rise speed, and the catalyst temperature becomes higher than the second temperature.
If the temperature is higher than the predetermined temperature, the target idle speed is gradually decreased by a constant value from the activation rise speed to the idle speed during normal control.

Further, the catalyst temperature acquiring means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature.

Further, the catalyst temperature acquiring means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes an exhaust temperature sensor provided in an exhaust pipe of the internal combustion engine for detecting an exhaust temperature, and a catalyst temperature based on the exhaust temperature. And estimating means for estimating the catalyst temperature.

Further, the catalyst temperature acquiring means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes a catalyst temperature estimating means for estimating and calculating the catalyst temperature based on at least information on the water temperature at the start of the internal combustion engine and the intake air amount. It is a thing.

Further, the idle speed increasing means of the catalyst temperature increasing control device for an internal combustion engine according to the present invention sets the activation increasing speed in accordance with the heat capacity of the exhaust system including the exhaust pipe.

Further, the idle speed increasing means of the catalyst temperature raising control device for the internal combustion engine according to the present invention increases the target idle speed by about 100 rpm from the normal idle speed as the activation rising speed. Is set.

Further, the catalyst temperature rise control device for an internal combustion engine according to the present invention further comprises an air-fuel ratio control means for controlling an air-fuel ratio of the internal combustion engine according to an operation state, Air-fuel ratio leaning means for setting the target air-fuel ratio of the internal combustion engine to an activation lean air-fuel ratio higher than the air-fuel ratio during normal control and higher than the stoichiometric air-fuel ratio.

Further, the catalyst temperature rise control device for an internal combustion engine according to the present invention further comprises an ignition timing control means for controlling the ignition timing of the internal combustion engine in accordance with the operation state, And ignition timing retarding means for correcting the target ignition timing of the internal combustion engine to an activation retarded ignition timing that is more retarded than the ignition timing during normal control over a second predetermined period.

Further, the ignition timing retarding means of the catalyst temperature rise control device for an internal combustion engine according to the present invention includes: first comparing means for comparing the catalyst temperature with a first predetermined temperature lower than the activation temperature;
Second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, and tailing for gradually changing the target ignition timing during target ignition timing switching control Means, and the tailing means comprises:
When the catalyst temperature is equal to or higher than the first predetermined temperature, the target ignition timing is gradually retarded by a constant value from the ignition timing in the normal control to the activation retard ignition timing, and the catalyst temperature is reduced to the second predetermined temperature. If it is higher than the target ignition timing, the target ignition timing is gradually advanced by a constant value from the activation retard ignition timing to the ignition timing at the time of the normal control.

Further, the ignition timing retarding means of the catalyst temperature rise control device for an internal combustion engine according to the present invention variably sets at least one of the activation retarded ignition timing and the second predetermined period according to the catalyst temperature. Things.

Further, the ignition timing retarding means of the catalyst temperature raising control device for an internal combustion engine according to the present invention intermittently corrects the target ignition timing to a retard side over a second predetermined period.

Further, the catalyst temperature rise control device for an internal combustion engine according to the present invention further comprises an ignition timing control means for controlling the ignition timing of the internal combustion engine in accordance with the operating condition, and an ignition timing control means for controlling when the catalyst temperature is lower than a predetermined temperature. And ignition timing retarding means for correcting the target ignition timing of the internal combustion engine to a retard side for a second predetermined period.

[0054]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The overall configuration of the device according to the first embodiment of the present invention is the same as that described above (see FIG. 38), and only a part of the operation program in ECU 14 differs.

In this case, catalyst temperature obtaining means for obtaining information corresponding to the temperatures of the catalysts 10 and 11 as the catalyst temperature TC is provided.
The temperature sensors (not shown) are provided at 0 and 11 for directly detecting the catalyst temperature TC.

The various sensors include an air flow sensor 5 for detecting the intake air amount Qa, and a crank angle signal CA.
(Crank angle sensor 1 for generating (engine speed Ne))
In addition to the above, a water temperature sensor for detecting a cooling water temperature TW of the engine 1 is provided.

The ECU 14 controls the air-fuel ratio A / F of the engine 1 in accordance with the operating condition. The ECU 14 controls the catalyst temperature TC to be lower than the predetermined temperature T2 corresponding to the activation temperature (activation start temperature: 130 ° C.). When the air-fuel ratio is low, the target air-fuel ratio A / F0 of the engine 1 is set higher than the air-fuel ratio during normal control and higher than the stoichiometric air-fuel ratio (= 14.7). ) Is provided.

The air-fuel ratio leaning means in the ECU 14 includes first comparing means for comparing the catalyst temperature TC with a first predetermined temperature T1 near the activation temperature, and means for comparing the catalyst temperature TC with the first predetermined temperature T1. A second comparing means for comparing with a second predetermined temperature T2 higher than the second predetermined temperature T2 corresponding to the activation temperature, wherein the catalyst temperature TC falls within a range between the first predetermined temperature T1 and the second predetermined temperature T2. Is set to the activation lean air-fuel ratio A / FL.

Therefore, the air-fuel ratio control means in the ECU 14 determines whether the target air-fuel ratio is high when the catalyst temperature TC is lower than the first predetermined temperature T1 and when the catalyst temperature TC is higher than the second predetermined temperature T2. Normal A / Fo (rich side)
Is set to A / Fn (14.7 or less).

That is, if the catalyst temperature TC is lower than the activation temperature (TC <T1), the ECU 14 determines the exhaust gas temperature TH based on the air-fuel ratio A / Fn during normal control (rich side).
Is raised to activate the catalyst, and after the catalyst temperature TC reaches the activation temperature (TC> T2), the normal air-fuel ratio A /
Feedback control by Fn is performed.

On the other hand, when the catalyst temperature TC shows a low value (T1 ≦ TC ≦ T2) near the activation temperature, the target air-fuel ratio A / Fo is set to the activated lean air-fuel ratio A / FL and the exhaust air By increasing the amount of oxygen, the catalyst reaction temperature is raised by the oxidation reaction to promote the activation of the catalyst.

The air-fuel ratio leaning means in the ECU 14 controls the target air-fuel ratio A / Fo when the control of the target air-fuel ratio A / Fo is switched.
A tailing means for gradually changing Fo is included.

That is, the tailing means in the air-fuel ratio leaning means sets the target air-fuel ratio A / Fo to the normal air-fuel ratio A / Fn when the catalyst temperature TC reaches the first predetermined temperature T1 or higher. To the activation lean air-fuel ratio A / FL by a constant value ΔF1.

Further, when the catalyst temperature TC reaches a temperature higher than the second predetermined temperature T2, the tailing means
The target air-fuel ratio A / Fo is gradually decreased by a constant value ΔF2 from the activated lean air-fuel ratio A / FL to the normal air-fuel ratio A / Fn.

Next, along with FIGS. 38 and 39, FIG.
The operation of the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing an air-fuel ratio control operation according to a catalyst temperature according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing step S3 (first tailing process with the activated lean air-fuel ratio A / FL as a target value) in FIG. 1, and FIG. 3 is a flowchart showing step S5 (FIG. 1) in FIG. It is a flowchart which shows the 2nd tailing process which made the air-fuel ratio A / Fn at the normal time the target value.

FIG. 4 is a timing chart showing changes over time of the cooling water temperature TW, the air-fuel ratio A / Fn during normal (control), the catalyst temperature TC, and the target air-fuel ratio A / Fo. In FIG. 4, the catalyst temperature TC increases as the cooling water temperature TW and the air-fuel ratio A / Fn in the normal state increase.

The activation lean air-fuel ratio A / FL (see dashed line) for promoting the activation of the catalyst is set to a value higher than the normal air-fuel ratio A / Fn (theoretical air-fuel ratio: 14.7). Is done. Here, the lean air-fuel ratio A / FL is about “16.
Although it is set to "0", it can be set to any value as long as it is a lean (higher) value than the stoichiometric air-fuel ratio (14.7).

As shown in FIG. 4, the target air-fuel ratio A / Fo is determined such that the catalyst temperature TC is equal to or higher than the first predetermined temperature T1 (approximately 70 ° C. lower than the activation temperature) and the second predetermined temperature T2 (to the activation temperature). (Approx. 130 ° C. corresponding) or less, the activation lean air-fuel ratio A is higher than the conventional value (broken line) obtained by the normal operation.
/ FL. Further, at the time of control switching at this time, the target air-fuel ratio A / Fo is gradually increased or decreased by tailing processing.

FIG. 5 to FIG. 8 are explanatory diagrams showing the time change of the engine state at the time of starting. FIG. 5 is a change curve of the engine speed Ne, FIG. 6 is a change curve of the air-fuel ratio A / F, and FIG.
8 shows a change curve of the upstream temperature TCf of the catalyst 10, and FIG. 8 shows a change curve of the downstream temperature TCr of the catalyst 10, respectively.

5 to 8, the horizontal axis represents time t, the solid line represents a change curve in the engine speed during normal control, and the dashed line represents the change curve in the engine speed increased by 200 rpm from the time during normal control. Are respectively shown. In each figure, a broken line is a change curve in the case of forcibly leaning.

FIG. 9 is a characteristic diagram showing a change in the exhaust gas temperature TH with respect to the air-fuel ratio A / F, and FIG. 10 is a characteristic diagram showing a change in the catalyst temperature TC with time. In FIG. 10, the solid line indicates the air-fuel ratio A /
F is a characteristic curve in a rich state (about 13.0), and a dashed line is a characteristic curve in an air-fuel ratio A / F in a lean state (about 16.0).

FIG. 11 is a characteristic diagram showing the change of the air-fuel ratio A / F with respect to the cooling water temperature TW [° C.]. In FIG. 11, the solid line is the characteristic curve of the air-fuel ratio A / Fn at normal time, and the one-dot chain line is the activation. The lean air-fuel ratio is A / FL (constant at 16.0).
However, the activation lean air-fuel ratio A / FL can be variably set.

FIG. 12 is an explanatory diagram showing a time change of the air-fuel ratio A / Fn immediately after the start in the normal control. In FIG. 12, the air-fuel ratio A / F is set to the rich side (<14.7) during the period from the start start time t1 (start motor drive time) to the actual engine start time t2, and the air-fuel ratio A / F becomes lean from the engine start time t2. Migrated to the side.

The correction amount α1 subtracted from the stoichiometric air-fuel ratio (= 14.7) after the start in FIG. 12 is an enrichment correction amount in consideration of the cold state immediately after the start of the engine 1; The amount α2 is an enrichment correction amount for stably warming up the engine 1. Each correction amount α1 and α2
Decreases as time t elapses.

In FIG. 1, the ECU 14 first determines the catalyst temperature TC detected by the temperature sensor as a first predetermined temperature T.
1 (for example, about 100 ° C.) and the catalyst temperature TC
Is lower than a first predetermined temperature T1 (step S1).

If it is determined that TC <T1 (ie, YES), the target air-fuel ratio A / Fo is reduced to the normal air-fuel ratio A / Fn because the catalyst temperature TC is too low and the catalyst hardly functions. (See FIG. 12) (step S
2), the activation of the catalyst is promoted by raising the combustion temperature.

In step S1, TC ≧ T1
If it is determined to be NO, it is close to the temperature at which the catalyst functions even though it has not reached the activation temperature. Therefore, in order to raise the catalyst reaction temperature, the first air-fuel ratio A / F1 (activated lean air-fuel ratio A (corresponding to A / FL) is executed as a target value A / Fo (step S3).

In the first tailing process (step S3), the target air-fuel ratio A / Fo is set to the activation lean air-fuel ratio A
/ FL (approximately 16.0). That is, the first air-fuel ratio A / F1 is not immediately set to the activation lean air-fuel ratio A / FL, but is set to FIG. 2 (described later).
As described above, the air-fuel ratio A / Fn in the normal state is gradually increased from the air-fuel ratio A / FL to the activated lean air-fuel ratio A / FL, thereby preventing deterioration of the running feeling.

Subsequently, the ECU 14 sets the catalyst temperature TC to the second predetermined temperature T2 corresponding to the activation temperature (about 180 ° C.).
(> T1), the catalyst temperature TC becomes the second predetermined temperature T
It is determined whether the temperature is higher than 2 (the activation temperature has been reached) (step S4).

If it is determined that TC> T2 (that is, YES), it is considered that the catalyst has been sufficiently activated, and the second air-fuel ratio A / F2 (corresponding to the normal air-fuel ratio A / Fn). ) Is executed as a target value A / Fo (step S5), and the processing routine of FIG. 1 is returned.

In the second tailing process (step S5), the second air-fuel ratio A / F2 is not immediately set to the normal air-fuel ratio A / Fn (rich side of 14.7 or less). As shown in FIG. 3 (described later), the second air-fuel ratio A
/ F2 (activated lean air-fuel ratio A / FL) is gradually reduced toward the normal air-fuel ratio A / Fn, thereby preventing the running feeling from deteriorating.

On the other hand, in step S4, TC ≦ T2
If determined to be NO, the process returns to the processing routine in FIG. 1 without executing step S5. As a result, within the range of T1 ≦ TC ≦ T2, the target air-fuel ratio A / Fo becomes the activated lean air-fuel ratio A /
FL (first air-fuel ratio A / F1) is set.

Although the first predetermined temperature T1 is set lower than the activation start temperature, the first predetermined temperature T1 may be set to a temperature (about 140 ° C.) higher than the activation start temperature.

The first tailing process (step S3) in FIG. 1 is specifically executed as shown in FIG. In FIG. 2, the tailing means first determines whether or not it is a predetermined timing to execute Step S3 (Step S11).

The predetermined timing for executing step S11 is set to a constant period, for example, every 100 msec, or to a timing synchronized with each ignition timing.

If the timing is not the predetermined timing (ie,
If the determination is NO, the processing routine of FIG. 2 is returned and the predetermined timing is reached (ie, YE).
S), the minimum value selection process (step S1)
According to 2), the first air-fuel ratio A / F1 is gradually set, and the processing routine of FIG. 2 is returned.

In the minimum value selection process (step S12), a value obtained by adding a constant value ΔF1 to the previous first air-fuel ratio A / F1 (n−1) (= A / F1 (n−1) + ΔF1).
And the activated lean air-fuel ratio A / FL (for example, 16.
0), whichever is smaller (rich side) (minimum value min) is set as the current first air-fuel ratio A / F1.

That is, immediately after the catalyst temperature TC reaches or exceeds the first predetermined temperature T1, the first air-fuel ratio A / F
Since the initial value of 1 is set to a value lower than the normal air-fuel ratio A / Fn (smaller than the activated lean air-fuel ratio A / FL), the previous value A / F1 (n-1) is fixed. The value obtained by adding ΔF1 becomes the minimum value min, and is selected and set as the current first air-fuel ratio A / F1.

Thereafter, the first air-fuel ratio A / F1 gradually increases (increases) by adding a constant value ΔF1 every time step S12 is executed, and the activated lean air-fuel ratio A / F1 is increased.
When FL is reached, it is clipped to the activated lean air-fuel ratio A / FL.

The constant value ΔF1 may be set to infinity to speed up leaning. Also, the initial value of the first air-fuel ratio A / F1 is set to be lower (to the rich side) than the normal air-fuel ratio A / Fn, but is the same as the normal air-fuel ratio A / Fn. It may be set to a value.

On the other hand, the second tailing process (step S5) in FIG. 1 is specifically executed as shown in FIG.
In FIG. 3, the tailing means first determines whether or not it is a predetermined timing at which step S5 is to be executed, similarly to step S11 described above (step S11A).

If the timing is not the predetermined timing (that is,
If it is determined as NO), the processing routine of FIG. 3 is directly returned, and it is the predetermined timing (that is, YE).
S), the maximum value selection process (step S12)
According to A), the second air-fuel ratio A / F2 is gradually reduced, and the processing routine of FIG. 3 is returned.

In the maximum value selection process (step S12A), a value obtained by subtracting a constant value ΔF2 from the previous second air-fuel ratio A / F2 (n−1) (= A / F2 (n−1) −ΔF).
2) and the normal air-fuel ratio A / Fn, whichever is larger (lean side) (maximum value max) is set as the second air-fuel ratio A / F2.

That is, immediately after the catalyst temperature TC reaches the second predetermined temperature T2, the initial value of the second air-fuel ratio matches the activated lean air-fuel ratio A / FL (the normal air-fuel ratio). A / Fn), the value obtained by subtracting the constant value ΔF2 from the previous value becomes the maximum value max,
Is set as the air-fuel ratio A / F2.

Thereafter, the second air-fuel ratio A / F2 is gradually enriched (decreased) by subtracting the constant value ΔF2 every time step S12A is executed, and the air-fuel ratio A / F at the normal time is increased.
When the air-fuel ratio has decreased to n, the air-fuel ratio A / Fn at the normal time is clipped.

The first predetermined temperature T1 corresponding to the catalyst activation start temperature (130 ° C.) is variably set according to the structure of the catalyst and the exhaust system. If the oxidation reaction is performed reliably in a lean state with the catalyst exceeding the activation start temperature, the second
Is a predetermined margin temperature (10 ° C.)
To 20 ° C.) (about 140 ° C. to 150 ° C.).

In this case, since the control period based on the activated lean air-fuel ratio A / FL at or above the activation temperature (or near the activation temperature) is started, even if the temperature rise of the exhaust system is delayed, the temperature of the oxidation reaction is reduced. Can sufficiently heat the catalyst.

After the catalyst temperature TC has reliably reached the activation temperature (the temperature at which the oxidation reaction is caused and the temperature can be increased), the second tailing process (step S12A) performs the normal air-fuel ratio A / A Fn can be restored.

When the oxidation reaction occurs when the temperature reaches the activation start temperature, the first predetermined temperature T1 is set to the second predetermined temperature T2 when the heat capacity CE of the exhaust system is relatively small.
Is a predetermined margin temperature (10 ° C. to 30 ° C.) from the activation temperature of the catalyst.
C.) is subtracted (approximately 100 to 120 C.).

In this case, the air-fuel ratio is controlled to the lean air-fuel ratio A / Fn at a relatively early timing immediately before the activation of the catalyst, so that the control based on the activated lean air-fuel ratio A / FL is not continued unnecessarily. Immediately before the catalyst is activated (or just at the time of activation), an oxidation reaction is surely caused, and the temperature of the catalyst can be effectively raised.

The initial value of the second air-fuel ratio A / F2 is
Although the case where the activation lean air-fuel ratio A / FL is set is shown, it may be set to a value (lean side) higher than the activation lean air-fuel ratio A / FL.

Also, by controlling the air-fuel ratio A / Fn at the time of starting (see FIG. 12), the actual air-fuel ratio A / F can be changed during normal control (solid line) at the beginning of starting as shown by the broken line in FIG. )
Is corrected to a richer side than the lean side (14.
7 or more).

Further, as shown by the broken line in FIG. 7, the upstream temperature TCf of the catalyst 10 becomes lower than that during the normal control due to the lean operation.

On the other hand, as shown in FIG. 8, the downstream side temperature TCr of the catalyst 10 is set to a period corresponding to the heat capacity CE of the exhaust system (18 seconds from 7 seconds to 25 seconds at a normal engine speed (solid line), Engine speed at the time of compensation for rise (dotted line)
At 8 seconds from 7 seconds to 15 seconds), and then gradually rises.

FIG. 9 shows the change of the exhaust gas temperature TH with respect to the air-fuel ratio A / F. In FIG. 9, the exhaust gas temperature TH is a value (about 12.0) richer than the stoichiometric air-fuel ratio (14.7). It is the maximum value. Accordingly, as the air-fuel ratio A / F increases (lean) from 12.0, the exhaust gas temperature TH gradually decreases.

When the air-fuel ratio A / F is made lean, since a large amount of oxygen is contained in the exhaust gas, HC and CO in the exhaust gas generate a large amount of heat due to an oxidation reaction in the catalyst.

Therefore, as shown in FIG. 10, the catalyst temperature T
After C reaches the activation temperature (= 130 ° C.), it is leaner (see dashed line) than when it is rich (see solid line).
In this case, the catalyst temperature TC increases more quickly.

As described above, the target air-fuel ratio A / Fo is corrected to be lean according to the catalyst temperature TC, and the normal air-fuel ratio A / Fn based on the operating state is maintained within a range where a minimum output torque can be maintained. Lean, and at least leaner than the stoichiometric air-fuel ratio.

As a result, as shown in FIG. 10, the temperature rise can be accelerated by promoting the oxidation reaction of HC and CO in the catalyst before and after the activation temperature of the catalyst. Therefore, early activation of the catalyst can be promoted.

Embodiment 2 In the first embodiment, the catalyst temperature TC is directly detected. However, the catalyst temperature TC may be estimated and calculated based on other various sensor (operating state) information. Hereinafter, a second embodiment of the present invention in which the catalyst temperature TC is estimated and calculated from the exhaust gas temperature TH will be described with reference to the drawings.

The basic configuration of the second embodiment of the present invention is the same as that described above, and only a part of the operation program in ECU 14 is different from the first embodiment. In this case, the catalyst temperature acquisition means is provided in the exhaust pipe 3 and detects an exhaust gas temperature TH (not shown).
4 and a catalyst temperature estimating means for estimating and calculating the catalyst temperature TC from the exhaust gas temperature TH.

As the various sensors, in addition to the exhaust gas temperature sensor, an intake air temperature sensor for detecting the intake air temperature TA, a water temperature sensor (not shown) for detecting the cooling water temperature TW, and the like are provided. In addition, the ECU 14 includes, in addition to the catalyst temperature estimating means,
At least the catalyst initial temperature (starting catalyst temperature) T from the starting water temperature TWs and the starting intake air temperature TAs of the engine 1.
An initial temperature estimating means for estimating and calculating Cs is included.

The rise in the catalyst temperature TC does not depend only on the exhaust gas temperature TH. For example, when the heat capacity of the exhaust system is large, it is suppressed by the absorption of heat energy by the exhaust system. Therefore, it is necessary to consider the exhaust system temperature TE in the estimation calculation of the catalyst temperature TC.

When the starting water temperature TWs and the starting intake air temperature TAs are substantially equal, the initial temperature estimating means in the ECU 14 determines the starting water temperature TWs as an initial catalyst temperature value TCs and an initial exhaust system temperature value (starting time). Estimation calculation is performed as (exhaust system temperature) TEs.

The initial temperature estimating means calculates the starting water temperature T.
If Ws and the intake air temperature TAs at the start are different, the initial value TCs of the catalyst temperature and the initial value TEs of the exhaust system temperature are estimated and calculated based on the deviation ΔTs between the water temperature at the start TWs and the intake air temperature TAs at the start.

Next, along with FIGS. 38 and 39, FIG.
The operation of the second embodiment of the present invention will be described with reference to FIGS. FIG. 13 is a flowchart showing an operation for estimating and calculating the catalyst temperature according to Embodiment 2 of the present invention.

FIG. 14 is an explanatory diagram showing the estimation process (steps S23 to S25) of the initial catalyst temperature TCs in FIG. 14, the horizontal axis represents the temperature deviation ΔTs between the cooling water temperature TWs and the intake air temperature TAs when the engine 1 starts.
(= TWs−TAs).

FIG. 15 is an explanatory diagram showing the state of consumption of the thermal energy (exhaust heat) of the exhaust gas.
Exhaust heat quantity QH due to exhaust gas is heat conduction quantity Q to the exhaust system.
E, the amount of heat conduction QC to the catalyst, and the amount of heat release QX to the outside air are consumed separately.

The heat conduction amount QE to the exhaust system is determined by the heat capacity CE and the heat resistance value RE of the exhaust system, and the heat conduction amount QC to the catalyst is determined by the heat capacity CC and the heat resistance value RC of the catalyst. Is the heat resistance value RX of the outside air.
Determined by

FIG. 16 is a characteristic diagram showing the relationship between the heat conduction amount QE to the exhaust system and the temperature rise ΔTE of the exhaust system. FIG. 17 is a graph showing the heat conduction amount QE to the exhaust system and the thermal time constant τE of the exhaust system. FIG. 4 is a characteristic diagram showing the relationship of FIG.

In FIG. 16, the total amount of heat conduction to the exhaust systemΣ
QE can be regarded as equivalent to the exhaust system temperature TE.
Therefore, the exhaust system temperature TE is given by the following equation (1) using the temperature rise ΔTE.

TE = TE (n−1) + ΔTE (1)

However, in the equation (1), TE (n−
1) is the previous value of the exhaust system temperature TE. Similarly, FIG.
, The exhaust system temperature TE corresponding to the total amount of heat conduction to the exhaust system ΣQE is given by the following equation (2) using a thermal time constant τE as a filter coefficient.

TE = TE (n-1) × (1-τE) + QE × βE × τE (2)

However, in the equation (2), βE is the specific heat of the exhaust system. In either of the above equations (1) and (2), the exhaust system temperature TE (total heat conduction to the exhaust system 系 QE)
Is calculated as a substantially matched value.

FIG. 18 is a characteristic diagram showing the relationship between the amount of heat conduction QC to the catalyst and the temperature rise ΔTC of the catalyst, and FIG. 19 shows the relationship between the amount of heat conduction QC to the catalyst and the thermal time constant τC of the catalyst. It is a characteristic diagram.

In FIG. 18, the total heat conduction to the catalyst ΔQ
The catalyst temperature TC corresponding to C is given by the following equation (3) using the temperature rise ΔTC.

TC = TC (n−1) + ΔTC (3)

However, in the equation (3), TC (n−
1) is the previous value of the catalyst temperature TC. Similarly, in FIG. 19, the catalyst temperature TC corresponding to the total amount of heat conduction to the catalyst ΣQC is given by the following equation (4) using the thermal time constant τC.

TC = TC (n−1) × (1−τC) + QC × βC × τC (4)

However, in the equation (4), βC is the specific heat of the catalyst. It can be seen that the catalyst temperature TC (total heat conduction amount to the catalystΣQC) is calculated as a substantially coincident value in both of the equations (3) and (4).

Referring to FIG. 13, first, the ECU 14 determines whether the start of the engine 1 is completed and whether a predetermined condition is satisfied (step S21). At this time, as a predetermined condition, it is determined whether a predetermined time has elapsed after the start of the engine 1 and it is time to perform a predetermined calculation.

In step S21, if it is determined that the predetermined condition after the start of the engine is satisfied (ie, YES), the starting water temperature T is obtained from the water temperature sensor and the intake air temperature sensor.
Ws and the start-up intake air temperature TAs are detected (step S
22).

At this time, in order to remove variations in the detected values, the starting water temperature TWs and the starting intake air temperature TAs may be detected over a predetermined period, and the detected values may be averaged.

Subsequently, the starting water temperature TWs and the starting intake air temperature TAs are compared to determine whether or not both are substantially equal (step S23).

If the starting water temperature TWs and the starting intake air temperature T
If there is almost no difference from As, it is considered that the vehicle has been left unattended until it matches the outside temperature, so that the temperature at this time can be assumed as the initial catalyst temperature TCs.

Therefore, in step S23, T
If it is determined that Ws ≒ TAs (that is, YES), the catalyst temperature TCs and the exhaust system temperature TEs (initial value) at the time of starting are regarded as the starting water temperature TWs, respectively, assuming that the engine 1 is in an initial state without a temperature rise. Set to the same value (step S24).

In step S23, if the difference ΔTs between the starting water temperature TWs and the starting intake air temperature TAs is equal to or greater than a predetermined value and it is determined that TWs ≠ TAs (ie, NO), the temperature of the engine 1 rises. Is large, the catalyst temperature TC and the exhaust system temperature TE (estimated value) are set according to the temperature deviation ΔTs (step S
25).

At this time, the initial catalyst temperature TCs is as shown in FIG.
As shown in FIG. 4, the estimation calculation is performed according to the temperature deviation ΔTs.
That is, when the temperature deviation ΔTs is equal to or less than 0, the catalyst temperature TCs is set to the starting water temperature TWs, and the temperature deviation ΔT
As s becomes larger than 0, the catalyst is considered to be in an active state, and the catalyst temperature TCs is set to a larger value.

Subsequently, the exhaust gas temperature TH is measured from the exhaust gas temperature sensor (step S26), and the exhaust gas temperature TH and the catalyst temperature TC are measured.
Using s and the intake air amount Qa measured by the air flow sensor 5, the total heat amount ΣQH by the exhaust gas is calculated by the following (5).
It is calculated as in the equation (step S27).

ΣQH = (TH−TCs) × Qa × βH (5)

In the equation (5), βH is the specific heat of the exhaust gas. If it is determined in step S21 that the predetermined condition after the completion of the start is not satisfied (that is, NO), it is no longer considered that the engine is being started.
The process immediately proceeds to step S26 without executing steps S22 to S25.

Next, the total heat quantity ΣQ calculated from the equation (5)
By subtracting the heat conduction amount QE to the exhaust system and the heat release amount QX to the outside air from H, the heat conduction amount QC to the catalyst is calculated as in the following equation (6) (step S28).

QC = ΣQH− (QE + QX) (6)

Finally, by performing an estimation calculation using the heat conduction amount QC to the catalyst and the heat conduction amount QE to the exhaust system, as shown in the following equations (7) and (8), the catalyst temperature TC and the exhaust system The temperature TE is calculated, and the processing routine of FIG. 13 is returned.

TC = TC (n−1) + QC (7) TE = TE (n−1) + QE (8)

However, in equations (7) and (8), T
C (n-1) and TE (n-1) are the previous values of the catalyst temperature TC and the exhaust system temperature TE, respectively. As described above, since the catalyst temperature TC can be estimated and calculated from the exhaust gas temperature TH detected by the exhaust gas temperature sensor, the same operational effects as those described above can be obtained.

As described above, the generated total heat quantity ΣQH is calculated from the air-fuel ratio and the intake air quantity Qa, and the catalyst temperature TC is calculated from the total heat quantity ΣQH in consideration of the heat capacity CE of the exhaust system.
Can be estimated.

Embodiment 3 In the second embodiment, the exhaust gas temperature TH is actually detected and the catalyst temperature TC is estimated and calculated. However, the exhaust gas temperature TH is calculated based on other various sensor information (operating state) without using the exhaust gas sensor. And catalyst temperature T
C may be estimated.

Hereinafter, a third embodiment of the present invention which does not require an exhaust gas temperature sensor will be described with reference to the drawings. In this case, EC
U14 includes catalyst temperature estimating means as catalyst temperature acquiring means, and estimates and calculates the catalyst temperature TC based on at least other various sensor information including the intake air amount Qa.

FIG. 20 is an explanatory diagram showing an operation for estimating and calculating the exhaust gas temperature TH according to the third embodiment of the present invention. FIG. 21 is an explanatory diagram showing an operation for setting the air-fuel ratio A / F according to the third embodiment of the present invention. FIG.

In FIG. 20, the exhaust gas temperature TH is estimated and calculated based on a two-dimensional map of the engine speed Ne and the engine load (intake amount Qa). That is, when at least one of the engine speed Ne and the engine load (intake amount Qa) included in the various sensor information (operating state) increases, the exhaust gas temperature TH is set to a large value.

In FIG. 21, the air-fuel ratio A / F is determined based on a two-dimensional map of the engine speed Ne and the engine load (intake amount Qa), similarly to the exhaust gas temperature TH.
However, the air-fuel ratio A / F is a value depending on the cooling water temperature TW as described above (see FIGS. 11 and 12).

Therefore, as described above, the air-fuel ratio A / F can be made lean in response to the activation temperature of the catalyst. Although the basic exhaust temperature TH is determined as shown in FIG. 20, the air-fuel ratio A / F in the cold state is a value corresponding to the water temperature TW. Qa, engine speed Ne) and air / fuel ratio A /
It is obtained by an estimation operation based on F.

As described above, the catalyst temperature TC can be estimated and calculated on the basis of the exhaust gas temperature TH obtained from the two-dimensional map shown in FIG.

Note that here, the engine load (intake air amount Q
The exhaust temperature TH and the catalyst temperature TC were estimated and calculated using only a). However, as described above, if other information such as the air-fuel ratio A / F is also taken into account, the catalyst temperature TC is more accurately estimated and calculated. can do.

As described above, the catalyst temperature estimating means in the ECU 14 sets the starting water temperature TWs as the initial catalyst temperature TC, generates the generated heat amount ΔQH calculated from the intake air amount Qa, and the heat capacity CE of the exhaust system. May be used to estimate and calculate the catalyst temperature TC.

The catalyst temperature estimating means includes an initial temperature estimating means for estimating the initial temperature TCs of the catalyst in the same manner as described above. The initial temperature estimating means of the catalyst is based on at least the starting water temperature TWs and the starting intake air temperature TAs. The TCs may be estimated and calculated.

That is, when the starting water temperature TWs is substantially equal to the starting intake air temperature TAs, the initial temperature estimating means estimates the starting water temperature TWs as the catalyst initial temperature TCs (see step S24 in FIG. 13). ).

In addition, the starting water temperature TWs and the starting intake air temperature T
If As differs from the predetermined temperature or more, the starting water temperature TW
The initial temperature TCs of the catalyst is estimated and calculated on the basis of the temperature difference ΔTs between s and the start-time intake air temperature TAs (see step S25 in FIG. 13).

As described above, at least the starting water temperature TW
Assuming the starting water temperature TWs as the initial catalyst temperature TC using the s, the intake air amount Qa, and the air-fuel ratio A / F, as described above,
By calculating the generated heat amount ΣQH based on the air-fuel ratio A / F, the catalyst temperature TC, and the intake air amount Qa, the generated heat amount ΣQH
Thus, the catalyst temperature TC can be estimated and calculated in consideration of the heat capacity CE of the exhaust system.

In this case, an expensive catalyst temperature sensor or exhaust gas temperature sensor having a high temperature to be detected and a wide detection temperature range is not required, so that the cost can be reduced in addition to the above-described effects.

Embodiment 4 In the first embodiment, the target air-fuel ratio A / Fo is set to promote the activation of the catalyst.
Is corrected to the lean side, but the target idle speed Nio during the idling operation may be corrected to the rising side.

Hereinafter, a fourth embodiment of the present invention in which the target idle speed Nio is corrected to increase will be described with reference to the drawings.
In this case, it is assumed that a temperature sensor (catalyst temperature acquisition unit) for directly detecting the catalyst temperature TC is provided as the various sensors described above.

The ECU 14 adjusts the opening of the ISC valve 8 (see FIG. 38) in accordance with the operating state to control the idle speed Ni, and when the condition for promoting the activation of the catalyst temperature TC is satisfied. , Target idle speed Ni
There is provided an idle speed increasing means for correcting o to a higher value than the normal idle speed Nin.

The idle speed increasing means in the ECU 14 compares the catalyst temperature TC with a first predetermined temperature T1a lower than the activation temperature, and the catalyst temperature TC corresponds to the activation temperature (the first comparison means). Higher than the predetermined temperature T1a)
Second comparing means for comparing with the second predetermined temperature T2a.

[0168] The idle speed increasing means is provided with a catalyst temperature TC.
Is within the range between the first predetermined temperature T1a and the second predetermined temperature T2a (T1a ≦ TC ≦ T2a), the target idle speed is maintained for a predetermined period until the catalyst temperature TC reaches the activation temperature. The number Nio is set to an activation rising rotation speed NiU higher than the idle rotation speed Nin during normal control.

Therefore, the idle control means in the ECU 14 determines that the catalyst temperature TC is lower than the first predetermined temperature T1a and that the catalyst temperature TC is lower than the second predetermined temperature T2a.
If higher, the target idle speed Nio is set to the normal value Nin.

On the other hand, when the catalyst temperature TC indicates a value equal to or lower than the activation temperature (T1a ≦ TC ≦ T2a), the target idle rotation speed Nio is set to the activation rising rotation speed NiU.
By increasing the exhaust gas temperature and increasing the amount of oxygen in the exhaust gas, the catalyst temperature TC is increased to promote activation.

The idle speed increasing means includes tailing means for gradually changing the target idle speed Nio during the switching control of the target idle speed Nio.

That is, the tailing means in the idling speed increasing means sets the catalyst temperature TC to the first predetermined temperature T1a.
When the above is reached, the target idle speed Nio is
From the idle speed Nin during normal operation to the activation rising speed N
It is gradually increased by a constant value ΔN1 until iU (= Nin + 100 rpm).

When the catalyst temperature TC reaches a temperature higher than the second predetermined temperature T2a, the tailing means changes the target idle speed Nio to the activation rise speed N
Constant value ΔN from iU to normal idle speed Nin
Decrease gradually by two.

Next, along with FIGS. 38 and 39, FIG.
The operation of the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 22 is a flowchart showing a process for correcting the idle speed Ni for promoting catalyst activation according to the catalyst temperature according to Embodiment 4 of the present invention.

FIG. 23 is a flowchart showing step S33 in FIG.
FIG. 24 is a flowchart showing (first tailing processing using the first rotation speed Ni1 as a target value), and FIG. 24 shows step S35 (second tailing processing using the second rotation speed Ni2 as a target value) in FIG. FIG.

FIGS. 22 to 24 respectively correspond to FIGS. 1 to 3 described above, and correspond to steps S31 to S35 in FIG.
Correspond to steps S1 to S5 (see FIG. 1), and steps S41 and S42 in FIG. 23 correspond to steps S11 and S12.
(See FIG. 2), and corresponds to step S41A in FIG.
S42A corresponds to steps S11A and S12A (see FIG. 3).

FIG. 25 is a timing chart showing time changes of the cooling water temperature TW, the idle speed Nin during normal (control), the catalyst temperature TC, and the target idle speed Nio. I have. In FIG. 25, changes in the cooling water temperature TW and the catalyst temperature TC are the same as those described above (see FIG. 4).

Activation increase rotation speed Ni for promoting catalyst activation
U (see the dashed line) is set to a value higher than the normal value Nin by, for example, about 100 rpm, and is set to decrease as time t elapses.

It is to be noted that the first and second predetermined temperatures T1a and T2a, which serve as comparison references for the catalyst temperature TC, may be set to the same values as the first and second predetermined temperatures T1 and T2, respectively. Good.

FIGS. 26 to 28 show a fourth embodiment of the present invention.
FIG. 7 is a diagram for explaining an operation of setting the idle speed Ni according to FIG. FIG. 26 is a characteristic diagram showing the relationship between the target idle speed Nio and the amount of generated heat ΔQ.
The amount of generated heat ΔQ increases as the target idle speed Ni increases.

FIG. 27 is a characteristic diagram showing a target idle speed Nio set according to the cooling water temperature TW.
Is the target idle speed Nio immediately after the start during normal control.
FIG. 4 is an explanatory diagram showing a time change of the scalar.

In FIG. 27, the broken line is a general target idle speed (about 700 rpm), the solid line is the characteristic curve of the idle speed Nin at normal time (at the time of normal increase correction), and the dashed line is the activation rise in the present invention. Rotational speed NiU (=
9 is a characteristic curve of (Nin + ΔNi (TW)).

The normal idle speed Nin is a value obtained by adding a rise correction amount to a general idle speed (broken line), and the rise correction amount decreases as the cooling water temperature TW increases. Therefore, the normal idle speed Nin
Converges to a general idle speed (700 rpm) when the cooling water temperature TW reaches about 80 ° C.

On the other hand, although the activation increase rotation speed NiU decreases as the cooling water temperature TW increases, the increase correction amount ΔNi (T
W) is set to a higher value. Activation rise rotation speed N
The increase correction amount ΔNi (TW) of iU is a function of the cooling water temperature TW, and in this case, slightly decreases as the cooling water temperature TW increases.

In FIG. 28, the target idle speed Nio immediately after the start in the normal control is 700 rpm during the period from the start start time t1 to the actual engine start time t2.
Is set to 1500r at the engine start time t2.
pm. The target idle speed Nio at the engine start time t2 is set to a value obtained by adding a rising component ΔNis immediately after the start to the basic speed Nib.

In FIG. 22, the ECU 14 (see FIG. 38) first determines that the catalyst temperature TC has reached the first predetermined temperature T1a.
(For example, about 70 ° C.) (step S31), and TC <T1a (that is, YE
If determined as S), the target idle speed Nio is set to the normal idle speed Nin (step S3).
2).

In step S31, TC ≧ T
If it is determined to be 1a (that is, NO), the first rotation speed Ni1 (corresponding to the activation rising rotation speed NiU) is set to the target value Ni.
The first tailing process is executed (step S).
33).

First tailing process (step S33)
In, the target idle speed Nio is gradually increased toward the activation rise speed NiU. That is, the first rotation speed Ni1 is not immediately set to the activation rising rotation speed NiU, but is changed from the normal idle rotation speed Nin to the activation rising rotation speed NiU as shown in FIG. 23 (described later). It is gradually increased to prevent deterioration of the running feeling.

Subsequently, the ECU 14 determines that the catalyst temperature TC is equal to the second predetermined temperature T2 corresponding to the activation temperature (about 130 ° C.).
It is determined whether the temperature is higher than a (> T1a) (the activation temperature has been reached) (step S34).

If TC> T2a (that is, YES)
Is determined, the catalyst is considered to be sufficiently activated, and the second rotation speed Ni2 (the normal idle rotation speed Ni
(corresponding to n) is set as the target value Nio, a second tailing process is executed (step S35), and the processing routine of FIG. 22 is returned.

Second tailing process (step S35)
In FIG. 24, the second rotation speed Ni2 is not immediately set to the normal idle rotation speed Nin, but as shown in FIG. 24 (described later), the second rotation speed Ni2 (activation rising rotation speed NiU). From the normal rotation speed Nin to reduce the running feeling.

On the other hand, in step S34, TC ≦ T
If it is determined as 2a (that is, NO), step S3
Without executing step 5, the processing routine of FIG. 22 is returned. As a result, within the range of T1a ≦ TC ≦ T2a, the target idle speed Nio becomes the activation rising speed N
It is set to iU (first rotation speed Ni1).

The first tailing process (step S33) in FIG. 22 is specifically executed as shown in FIG.
In FIG. 23, the tailing means firstly performs step S
It is determined whether or not it is a predetermined timing to execute step 33 (step S41). If it is determined that the timing is not the predetermined timing (that is, NO), the processing routine of FIG. 23 is returned as it is.

If it is determined in step S41 that the timing is the predetermined timing (ie, YES), the first rotation speed Ni1 is gradually increased by the minimum value selection processing (step S42), and the processing in FIG. Return the routine.

In the minimum value selection process (step S42), a fixed value Δ is added to the previous first rotation speed Ni1 (n-1).
A value obtained by adding N1 (= Ni1 (n-1) + ΔN1);
The smaller value (minimum value min) of the activation rise rotation speed NiU is set as the current first rotation speed Ni1.

That is, initially, the first rotation speed Ni1 is set to a value lower than the normal idle rotation speed Nin (smaller than the activation rising rotation speed NiU). The value obtained by adding ΔN1 is the minimum value m
in, and is selected and set as the current first rotation speed Ni1.

Thereafter, the first rotation speed Ni1 is gradually increased by the addition of the constant value ΔN1 every time step S42 is performed, and when the activation rotation speed NiU is reached, the first rotation speed Ni1 is increased. Clipped to NiU.

The constant value ΔN1 may be set to infinity in order to increase the speed quickly. Also, the initial value of the first rotation speed Ni1 may be set to the same value as the normal idle rotation speed Nin.

On the other hand, the second tailing process (step S35) in FIG. 22 is specifically executed as shown in FIG. In FIG. 24, the tailing means first determines whether or not it is a predetermined timing at which step S35 is to be executed (step S41A). If it is determined that the timing is not the predetermined timing (ie, NO), the processing in FIG. Return the routine.

If it is determined in step S41A that the timing is a predetermined timing (ie, YES),
The second rotation speed Ni2 is gradually set by the maximum value selection processing (step S42A), and the processing routine of FIG. 24 is returned.

In the maximum value selection process (step S42A), a value obtained by subtracting a constant value ΔN2 from the previous second rotation speed Ni2 (n−1) (= Ni2 (n−1) −ΔN2).
The larger value (maximum value max) of the normal idle speed Nin and the normal idle speed Nin is the second speed Ni2
Is set as

That is, initially, since the second rotation speed Ni2 is equal to the activation rising rotation speed NiU (greater than the normal idle rotation speed Nin), the constant value ΔN2 is subtracted from the previous value. The value becomes the maximum value max,
This is set as the current second rotation speed Ni2.

Thereafter, every time step S42A is executed, the second rotation speed Ni2 gradually decreases by subtracting the constant value ΔN2, and when the second rotation speed Ni2 decreases to the normal idle speed Nin, the normal idle speed Nin is reduced. It is clipped to the rotation speed Nin.

As a result, the actual target idle speed N
As shown in FIG. 25, io is set to the activation increase rotation speed NiU within the range of T1a ≦ TC ≦ T2a. Therefore, similarly to the above, the catalyst temperature TC can be effectively raised to the activation temperature.

Embodiment 5 In the fourth embodiment, the activation rise rotation speed NiU is set to Nin + 100 rpm. However, if the fuel consumption drivability does not cause a problem, the rotation speed is increased to another rotation speed determined from the heat capacity CE of the exhaust system. May be set.

That is, if the amount of increase in the idling speed is set too large, noise will be generated and the fuel consumption will be deteriorated. Therefore, the amount of increase in the idling speed should be within the range that is most efficient and does not cause any problem. Is set to

Embodiment 6 FIG. In the fourth embodiment, the temperature sensor that directly detects the catalyst temperature TC is used as the catalyst temperature acquisition means. However, the catalyst temperature TC is estimated from the exhaust temperature TH by using the exhaust temperature sensor that detects the exhaust temperature TH. Alternatively, the catalyst temperature TC may be estimated from another operating state.

Embodiment 7 FIG. In the fourth embodiment, the target idle rotation speed Nio is increased to the activation increase rotation speed NiU in order to promote the increase in the catalyst temperature TC. However, in the first embodiment (the target air-fuel ratio A / Fo is set to the activation lean air-fuel ratio A / FL).

FIG. 29 shows Embodiment 7 of the present invention in which the idling speed increase correction and the air-fuel ratio lean correction are combined.
FIG. 5 is an explanatory diagram showing the control operation of FIG. 5, and the horizontal axis corresponds to the catalyst temperature TC.

Here, a case is shown in which predetermined temperatures T1a and T2a for correcting an increase in idle speed and predetermined temperatures T1 and T2 for correcting lean air / fuel ratio are different from each other.
Particularly, two control examples when the predetermined temperatures T2a and T1 are different are shown.

In FIG. 29, each of the predetermined temperatures T2a, T1
Is set to satisfy the relationship of T2a <T1, when the catalyst temperature TC is relatively low (T1a <TC <
At T2a), the idling speed increase correction (Nio ← N)
iU), and the region (T) where the catalyst temperature TC is relatively high
1 <TC <T2, the air-fuel ratio lean correction (A / F
o ← A / FL) is executed.

In this case, after the catalyst temperature TC is raised to some extent by the idling speed increase correction, the catalyst temperature TC is further raised by the air-fuel ratio lean correction, so that the catalyst can be reliably raised to the activation temperature. .

On the other hand, when the predetermined temperatures T2a and T1 are smaller than T1 <
When the relationship is set so as to satisfy the relationship of T2a, a region where the catalyst temperature TC indicates an intermediate temperature (T1 <TC <T2a)
At idle speed increase correction (Nio ← NiU)
And the air-fuel ratio lean correction (A / Fo ← A / FL) are executed.

In this case, the intermediate temperature range (T1 <TC <T
In 2a), the amount of heat supplied to the catalyst is significantly increased due to the synergistic effect of increasing the amount of oxygen due to lean air-fuel ratio and increasing the amount of supplied air due to an increase in idle speed, and the oxidation reaction of the catalyst due to excess air (oxygen) Promotes,
The increase in the catalyst temperature can be further promoted.

As described above, by combining the idling speed increase correction and the air-fuel ratio lean correction, the increase in the catalyst temperature can be further promoted by the synergistic effect of the two, and the catalyst temperature TC can be quickly increased to the activation temperature. Can be reached.

Embodiment 8 FIG. In the seventh embodiment, the increase in the idling speed and the lean correction of the air-fuel ratio are combined in order to promote the increase in the catalyst temperature TC. The exhaust temperature may be increased.

The control operation of the eighth embodiment of the present invention to which the ignition timing is retarded will be described below. In this case, the ECU 14 (see FIG. 38) includes an ignition timing control unit that controls the ignition timing of the engine 1 according to the operating state;
When the catalyst temperature TC is lower than the predetermined temperature, the ignition timing retard for correcting the target ignition timing Po to the activation retard ignition timing PR on the retard side of the ignition timing Pn during the normal control over the second predetermined period. Corner means.

The ignition timing retarding means in the ECU 14 includes first comparing means for comparing the catalyst temperature TC with a first predetermined temperature T1b lower than the activation temperature, and an ignition timing delaying means in the ECU 14 for comparing the catalyst temperature TC with the first predetermined temperature T1b. A second comparing means for comparing the temperature with a second predetermined temperature T2b which is higher and corresponding to the activation temperature; and a tailing means for gradually changing the target ignition timing Po during switching control of the target ignition timing Po.

When the catalyst temperature TC is equal to or higher than the first predetermined temperature T1b, the tailing means sets the target ignition timing Po to
From the ignition timing Pn during normal control to the activation retard ignition timing PR
Until the catalyst temperature TC is higher than the second predetermined temperature T2b, the target ignition timing Po is set to the activation retard ignition timing PR.
To the ignition timing Pn at the time of normal control, the control angle is gradually advanced (control amount is increased) by a constant value ΔP2.

[0220] The second predetermined period in which the ignition timing is retarded is set according to the exhaust gas temperature TH or the catalyst temperature TC so that no drivability problem occurs.
Further, the ignition timing retarding means in the ECU 14 variably sets at least one of the activation retarded ignition timing PR and the second predetermined period according to the catalyst temperature TC.

FIGS. 30 to 35 show an eighth embodiment of the present invention.
FIG. 6 is a diagram for explaining a control operation according to FIG. FIG. 30 is a flowchart showing the ignition timing correction process for accelerating catalyst activation according to the catalyst temperature TC. Here, for simplification, only the ignition timing retard correction process is shown.

FIG. 31 is a flowchart showing step S53 in FIG.
FIG. 32 is a flowchart showing (first tailing processing using first ignition timing P1 as a target value) FIG. 32 shows step S55 in FIG. 30 (second tailing processing using second ignition timing P2 as a target value). FIG.

FIG. 33 is a characteristic diagram showing the change of the target ignition timing Po with respect to the cooling water temperature TW, and the advanced side (corresponding to the target ignition timing Po) indicates the advance side in the positive direction. In FIG. 33, a solid line shows a change curve of the ignition timing Pn during normal control, and a dashed line shows a change curve of the activation retard ignition timing PR.

The normal ignition timing Pn (see the solid line) shifts to the retard side as the coolant temperature TW rises, and becomes substantially constant when the coolant temperature TW reaches about 80 ° C. on the other hand,
Although the activation retarded ignition timing PR (see the dashed line) is retarded more than the normal ignition timing Pn, the cooling water temperature T
The retard correction amount decreases as W increases.

FIG. 34 is a timing chart showing changes over time of the catalyst temperature TC and the target ignition timing Po. FIG.
In 4, the target ignition timing Po is determined so that the predetermined temperature TC is equal to the first temperature.
The activation retard ignition timing PR is set during a period between the predetermined temperature T1b and the second predetermined temperature T2b.

FIG. 35 is a graph showing the correction of the increase in idle speed (Nio).
← NiU) and air-fuel ratio lean correction (A / Fo ← A / F)
L) and the ignition timing retard correction (Po ← PR) are combined to explain the control operation, and the horizontal axis corresponds to the catalyst temperature TC.

FIG. 35 shows the case where the predetermined temperatures serving as the comparison reference for the catalyst temperature TC are different.
The first and second predetermined temperatures may be set to the same value.

In FIG. 30, the ECU 14 first determines whether or not the catalyst temperature TC is lower than a first predetermined temperature T1b (step S51), and TC <T1b (that is, TC <T1b).
If the determination is YES, the target ignition timing Po is set to the normal ignition timing Pn (step S52).

At step S51, TC ≧ T
If it is determined to be 1b (that is, NO), the first ignition timing P1 (corresponding to the activation retarded ignition timing PR) is set to the target value Po.
Is executed (step S5).
3).

First tailing processing (step S53)
, The target ignition timing Po is the activation retard ignition timing P
It is gradually reduced (retarded) toward R. That is, the first ignition timing P1 is not immediately set to the activation retarded ignition timing PR, but as shown in FIG. 31 (described later), the activation retarded ignition timing PR is changed from the normal ignition timing Pn. , And the traveling feeling is prevented from deteriorating.

Subsequently, the ECU 14 determines whether or not the catalyst temperature TC is higher than a second predetermined temperature T2b (> T1b) (step S54), and TC> T2b (ie, Y> T2b).
ES), the second tailing process is performed with the second ignition timing P2 (corresponding to the normal ignition timing Pn) as the target value Po (step S55), and the processing routine of FIG. 30 is returned. I do.

The second tailing process (step S55)
In FIG. 32, the second ignition timing P2 is not immediately set to the normal ignition timing Pn.
The second ignition timing P2 (the activation retard ignition timing P
R) gradually increases (advanced) toward normal ignition timing Pn
This prevents the running feeling from being deteriorated.

On the other hand, in step S54, TC ≦ T
If it is determined to be 2a (that is, NO), step S5
The processing routine of FIG. 30 is returned without executing step 5. Thus, the target ignition timing Po is set to the activation retard ignition timing PR (first ignition timing P1) within the range of T1b ≦ TC ≦ T2b.

The first tailing process (step S53) in FIG. 30 is specifically executed as shown in FIG.
In FIG. 31, the tailing means in the ECU 14 first determines whether or not it is a predetermined timing at which step S53 is to be executed (step S61). The processing routine of FIG. 31 is returned.

If it is determined in step S61 that the timing is the predetermined timing (ie, YES), the first ignition timing P1 is gradually reduced by the maximum value (maximum advance value) selection process (step S62). Then, the processing routine of FIG. 31 is returned.

In the maximum value selection processing (step S62), a value obtained by subtracting a constant value ΔP1 from the previous first ignition timing P1 (n−1) (= P1 (n−1) −ΔP1) is obtained.
The larger value (advance side max) of the activation retarded ignition timing PR is set as the current first ignition timing P1.

That is, initially, the first ignition timing P1 is the normal ignition timing Pn (the activation retard ignition timing P
R is set to a larger value on the advance side than R), the value obtained by subtracting the constant value ΔP1 from the previous value is the maximum value ma.
x, which is selected and set as the current first ignition timing P1.

Thereafter, the first ignition timing P1 is gradually reduced (retarded) by subtracting the constant value ΔP1 every time step S62 is executed, and when the activation retard ignition timing PR is reached. Is clipped to the activation retard ignition timing PR.

On the other hand, the second tailing process (step S55) in FIG. 30 is specifically executed as shown in FIG. In FIG. 32, the tailing means first determines whether or not it is a predetermined timing at which step S55 is to be executed (step S61A), and if it is determined that the timing is not the predetermined timing (ie, NO), the processing in FIG. Return the routine.

If it is determined in step S61A that it is the predetermined timing (ie, YES),
By the minimum value selection process (step S62A), the second ignition timing P2 is set to be gradually increased, and the process routine of FIG. 32 is returned.

In the minimum value selection process (step S62A), a value obtained by adding a constant value ΔP2 to the previous second ignition timing P2 (n−1) (= P2 (n−1) + ΔP2) is obtained.
The smaller value (minimum value mim) of the normal ignition timing Pn is set as the second ignition timing P2.

That is, initially, since the second ignition timing P2 coincides with the activation retarded ignition timing PR (smaller than the normal ignition timing Pn), a constant value ΔP2 is added to the previous value. The value becomes the minimum value mim, and the second
Is set as the ignition timing P2.

Thereafter, every time step S62A is executed, the second ignition timing P2 is gradually increased (advanced) by adding a constant value ΔP2, and when the second ignition timing P2 has increased to the normal ignition timing Pn, It is clipped to the normal ignition timing Pn.

As a result, the actual target ignition timing Po becomes
As shown in FIG. 34, the activation retarded ignition timing PR is set within the range of T1b ≦ TC ≦ T2b. Therefore, similarly to the above, the catalyst temperature TC can be effectively raised to the activation temperature.

Predetermined temperatures T1b and T2b serving as comparison standards for activation determination can be set, for example, as shown in FIG. In FIG. 35, the range of the predetermined temperatures T1b and T2b for correcting the ignition timing retard is set within the range of the predetermined temperatures T1a and T2a for correcting the increase in the idling speed.

Here, the case where the predetermined temperature T1 for the air-fuel ratio lean correction is set so as to satisfy the relationship of T2b <T2a <T1, and the case where the predetermined temperature T1 is set so as to satisfy the relationship of T1 <T2b <T2a. Two control examples are shown.

For example, each predetermined temperature is set to T2b <T2a
When the relationship of <T1 is set, in the region where the catalyst temperature TC is relatively low (T1a <TC <T2a), the idling speed increase correction (Nio ← NiU) and the ignition timing retard correction (Po ← PR) are performed. Then, in the region where the catalyst temperature TC is relatively high (T1 <TC <T2), the air-fuel ratio lean correction (A / Fo ← A / FL) is performed.

On the other hand, each predetermined temperature is defined as T1 <T2b <T2
In the case where the relationship is set to a, in the region where the catalyst temperature TC indicates the intermediate temperature (T1 <TC <T2b), the idling speed increase correction (Nio ← NiU) and the air-fuel ratio leaning correction (A / Fo ← A) / FL) and ignition timing retard correction (P
o ← PR) are all executed.

In this case, the intermediate temperature range (T1 <TC <T
In 2b), the amount of heat supplied to the catalyst is significantly increased due to the synergistic effect of the increase in the amount of supplied air and the increase in the exhaust gas temperature by each correction control, and the oxidation reaction of the catalyst is promoted due to excess air (oxygen). In addition, the catalyst temperature can be further increased.

As described above, by combining the ignition timing retard correction with the idle speed increase correction and the air-fuel ratio lean correction, the increase in the catalyst temperature can be further promoted. Can be reached quickly.

Embodiment 9 FIG. In the eighth embodiment, the target ignition timing Po is only corrected to the retard side over the second predetermined period. However, the target ignition timing Po is intermittently shifted to the retard side over the second predetermined period. It may be corrected.

A ninth embodiment of the present invention in which the target ignition timing Po is intermittently retarded will be described below with reference to the drawings.
36 and 37 are a flowchart and a timing chart showing a control operation according to Embodiment 9 of the present invention.

In FIG. 36, steps S73 and S76 correspond to steps S53 and S53 in FIG. 30, respectively.
(See FIG. 31) and step S55 (see FIG. 32).

In FIG. 37, the target ignition timing Po returns to the normal ignition timing Pn in response to the set (on) state of the flag F for returning the ignition timing, and responds to the clear (off) state of the flag F. Then, the process proceeds to the activation retard ignition timing PR.

In FIG. 36, first, the ignition timing correction means in the ECU 14 determines whether or not it is a predetermined timing for executing the processing routine of FIG. 36 (step S71), and determines that it is not the predetermined timing (ie, NO). If
As it is, the processing routine of FIG. 36 is returned.

If it is determined in step S71 that it is the predetermined timing (ie, YES), it is determined whether the flag F is cleared (F = 0) (step 72).

If it is determined that F = 0 (ie, YES), the target ignition timing Po is changed to the activation retard ignition timing PR
In order to shift to the tailing, the first ignition timing P1 is set as the target ignition timing Po (the processing of FIG. 31 is executed) (step S73).

By repeatedly executing step S73, the first ignition timing P1 is reduced (retarded) as described above. Subsequently, it is determined whether or not the first ignition timing P1 coincides with the activation retard ignition timing PR (step S74).
If it is determined that 1 ≠ PR (that is, NO), the processing routine of FIG. 36 is directly returned.

At step S74, P1 = P
If it is determined to be R (that is, YES), the flag F is set to "1" (step S75), and the second ignition timing is set to return the target ignition timing Po to the normal ignition timing Pn. P2 is set as the target ignition timing Po (the processing of FIG. 32 is executed) (step S76).

On the other hand, if it is determined in step 72 that F = 1 (ie, NO), step S76 is immediately performed.
Proceed to. By repeatedly executing step S76, the second ignition timing P1 increases (advances) as described above.

Subsequently, it is determined whether or not the second ignition timing P2 coincides with the normal ignition timing Pn (step S7).
7) If it is determined that P1 ≠ Pn (that is, NO),
As it is, the processing routine of FIG. 36 is returned.

In step S77, P2 = P
If n (ie, YES) is determined, the flag F is cleared to "0" (step S78), and the processing routine in FIG. 36 is returned).

As a result, the target ignition timing Po is set as shown in FIG.
In response to the turning on and off of the flag F, the tailing transition (correction to the retard side) to the activation retard ignition timing PR is performed intermittently from the control start time t0.

Therefore, it is possible to increase the amount of heat supplied to the catalyst and promote the increase in the catalyst temperature TC while minimizing the deterioration of drivability due to the ignition timing retard correction.

If the ignition timing is intermittently controlled to the retard side over a second predetermined period according to the exhaust gas temperature TH or the catalyst temperature TC, the increase in the catalyst temperature TC can be more effectively promoted. can do.

Embodiment 10 FIG. Embodiment 8
In the above, the idle speed increase correction, the air-fuel ratio lean correction, and the ignition timing retard correction are combined, but except for the air-fuel ratio lean correction, only the idle speed rise correction and the ignition timing retard correction are combined. Of course, it goes without saying that a synergistic effect similar to that described above has a remarkable effect.

[0267]

As described above, according to the first aspect of the present invention, a catalyst comprising a three-way converter provided in an exhaust pipe of an internal combustion engine and information corresponding to the temperature of the catalyst are acquired as a catalyst temperature. Means for obtaining catalyst temperature, various sensors for detecting the operating state of the internal combustion engine, air-fuel ratio control means for controlling the air-fuel ratio of the internal combustion engine in accordance with the operating state, and a catalyst temperature corresponding to the activation temperature of the catalyst. If lower than the temperature,
Air-fuel ratio leaning means for correcting the target air-fuel ratio of the internal combustion engine to the lean side in order to promote the activation of the catalyst; various sensors detect at least intake air amount information corresponding to the load of the internal combustion engine; When the catalyst temperature is lower than a predetermined temperature, the air-fuel ratio leaning means sets the target air-fuel ratio higher than the air-fuel ratio during normal control and the stoichiometric air-fuel ratio. Since the activation lean air-fuel ratio is set higher than that, the catalyst temperature can be quickly raised at the time of startup, and there is an effect that a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy exhaust gas regulations can be obtained. .

According to a second aspect of the present invention, in the first aspect, the air-fuel ratio leaning means includes a first comparing means for comparing the catalyst temperature with a first predetermined temperature near the activation temperature. Second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, wherein the catalyst temperature is equal to the first predetermined temperature and the second predetermined temperature. When the target air-fuel ratio is within the range between the target air-fuel ratio and the activation lean air-fuel ratio, the catalyst temperature can be raised quickly and effectively at the time of starting, and the exhaust gas regulation is sufficiently regulated. Thus, there is an effect that a catalyst temperature rise control device for an internal combustion engine that can satisfy the above condition is obtained.

According to a third aspect of the present invention, in the second aspect, the air-fuel ratio leaning means includes tailing means for gradually changing the target air-fuel ratio at the time of target air-fuel ratio switching control. When the catalyst temperature is equal to or higher than the first predetermined temperature, the means gradually increases the target air-fuel ratio by a constant value from the air-fuel ratio at the time of the normal control to the activated lean air-fuel ratio. If it is higher than the temperature,
Since the target air-fuel ratio is gradually decreased by a constant value from the activated lean air-fuel ratio to the air-fuel ratio during normal control,
There is an effect that a catalyst temperature increase control device for an internal combustion engine that can sufficiently satisfy exhaust gas regulations without impairing drivability is obtained.

According to a fourth aspect of the present invention, in the first aspect, the catalyst temperature obtaining means includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature.
There is an effect that a catalyst temperature rise control device for an internal combustion engine that can quickly and effectively raise the catalyst temperature at the time of starting and sufficiently satisfy exhaust gas regulations can be obtained.

According to a fifth aspect of the present invention, in the first aspect, the catalyst temperature acquiring means is provided in an exhaust pipe of the internal combustion engine to detect an exhaust gas temperature, and based on the exhaust gas temperature. Since the catalyst temperature estimating means for estimating and calculating the catalyst temperature is included, the catalyst temperature can be raised quickly and effectively at the time of start-up using a relatively inexpensive exhaust gas temperature sensor without increasing the cost. There is an effect that a catalyst temperature increase control device for an internal combustion engine that can sufficiently satisfy the regulations can be obtained.

According to a sixth aspect of the present invention, in the first aspect, the catalyst temperature obtaining means includes a catalyst temperature estimating means for estimating and calculating the catalyst temperature based on at least the intake air amount information of the internal combustion engine. Eliminates the need for special sensors
There is an effect that a catalyst temperature rise control device for an internal combustion engine that can quickly and effectively raise the catalyst temperature at the time of startup without increasing the cost and sufficiently satisfy the exhaust gas regulations can be obtained.

According to a seventh aspect of the present invention, in the sixth aspect, the catalyst temperature estimating means includes an initial temperature estimating means for estimating and calculating an initial temperature of the catalyst, and the initial temperature estimating means includes at least an internal combustion engine. The initial temperature of the catalyst is estimated and calculated based on the starting water temperature and the starting intake air temperature, so that the catalyst temperature can be raised quickly and effectively at the start without increasing the cost, and the exhaust gas regulation This is effective in obtaining a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy the following conditions.

According to claim 8 of the present invention, in claim 6, when the starting water temperature and the starting intake air temperature are substantially equal, the initial temperature estimating means sets the starting water temperature as the catalyst initial temperature. When the starting water temperature and the starting intake air temperature are different from each other by estimating calculation, the initial temperature of the catalyst is estimated and calculated based on the deviation between the starting water temperature and the starting intake air temperature. Thus, the catalyst temperature can be raised quickly and effectively at the time of starting, and there is an effect that a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy the exhaust gas regulations can be obtained.

According to a ninth aspect of the present invention, in the sixth aspect, the catalyst temperature estimating means sets the water temperature at the start of the internal combustion engine as the initial catalyst temperature and calculates the water temperature calculated from the intake air amount information. Since the catalyst temperature is estimated and calculated based on the heat quantity and the heat capacity of the exhaust system including the exhaust pipe, the catalyst temperature can be raised quickly and effectively at startup without increasing the cost, and the exhaust gas There is an effect that a catalyst temperature increase control device for an internal combustion engine that can sufficiently satisfy the regulations can be obtained.

According to a tenth aspect of the present invention, in the first aspect, the predetermined temperature is set to a value obtained by adding a predetermined margin temperature to an activation temperature of the catalyst, so that the catalyst temperature is effectively raised. Thus, there is an effect that a catalyst temperature increase control device for an internal combustion engine that can sufficiently satisfy exhaust gas regulations can be obtained.

According to the eleventh aspect of the present invention, in the first aspect, the predetermined temperature is set to a value obtained by subtracting a predetermined margin temperature from the activation temperature of the catalyst, so that the catalyst temperature is effectively raised. Thus, there is an effect that a catalyst temperature increase control device for an internal combustion engine that can sufficiently satisfy exhaust gas regulations can be obtained.

According to a twelfth aspect of the present invention, there is provided a catalyst comprising a three-way converter provided in an exhaust pipe of an internal combustion engine, and a catalyst temperature acquisition for acquiring information corresponding to the temperature of the catalyst as a catalyst temperature. Means, various sensors for detecting the operating state of the internal combustion engine, idle control means for controlling the idle speed of the internal combustion engine according to the operating state, and when the catalyst temperature is lower than a predetermined temperature corresponding to the activation temperature of the catalyst. Further, in order to promote activation of the catalyst, there is provided idle speed increasing means for correcting the target idle speed of the internal combustion engine to a higher side than the idle speed during normal control, and the idle speed increasing means comprises: When the catalyst temperature is lower than the predetermined temperature, the target idle speed is higher than the idle speed during normal control for a predetermined period until the catalyst temperature reaches the activation temperature. Since the rotation speed is set to be increased, the catalyst temperature can be quickly increased during the idling operation at the time of starting, and the catalyst temperature rise control device for the internal combustion engine which can sufficiently satisfy the exhaust gas regulation can be obtained. effective.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the idle speed increasing means compares the catalyst temperature with a first predetermined temperature lower than the activation temperature.
And a second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, so that the catalyst temperature is equal to the first predetermined temperature and the second predetermined temperature. When the temperature is within the range between the predetermined temperature and the target idle speed, the target idle speed is set to the activation rise speed,
In the idling operation at the time of starting, the catalyst temperature can be raised quickly and effectively, and the catalyst temperature rise control device for the internal combustion engine which can sufficiently satisfy the exhaust gas regulation can be obtained.

According to a fourteenth aspect of the present invention, in the thirteenth aspect, the idle speed increasing means includes tailing means for gradually changing the target idle speed at the time of controlling the switching of the target idle speed. When the catalyst temperature is equal to or higher than the first predetermined temperature, the tailing means gradually increases the target idle speed by a constant value from the idle speed at the time of the normal control to the activation rise speed, and the catalyst temperature is increased. When the temperature is higher than the second predetermined temperature, the target idle speed is gradually decreased by a constant value from the activation rise speed to the idle speed during normal control. A catalyst temperature raising system for an internal combustion engine that can quickly and effectively raise the catalyst temperature without impairing drivability and sufficiently satisfy exhaust gas regulations. The effect of device is obtained.

According to a fifteenth aspect of the present invention, in the twelfth aspect, the catalyst temperature acquiring means includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature. There is an effect that a catalyst temperature rise control device for an internal combustion engine that can quickly and effectively raise the catalyst temperature and sufficiently satisfy the exhaust gas regulations can be obtained.

According to a sixteenth aspect of the present invention, in the twelfth aspect, the catalyst temperature obtaining means is provided in an exhaust pipe of the internal combustion engine to detect an exhaust temperature, and based on the exhaust temperature. And a catalyst temperature estimating means for estimating and calculating the catalyst temperature.
There is an effect that a catalyst temperature rise control device for an internal combustion engine that can quickly and effectively raise the catalyst temperature during idling at the time of startup without incurring a cost increase and sufficiently satisfy exhaust gas regulations can be obtained. .

According to a seventeenth aspect of the present invention, in the twelfth aspect, the catalyst temperature obtaining means is configured to estimate and calculate the catalyst temperature based on at least the water temperature at the start of the internal combustion engine and the intake air amount information. Therefore, a special sensor is not required, and the catalyst temperature can be raised quickly and effectively at the time of idling at the time of starting without increasing the cost, and the internal combustion engine can sufficiently satisfy the exhaust gas regulation. There is an effect that a catalyst temperature rise control device can be obtained.

According to claim 18 of the present invention, in claim 12, the idle speed increasing means sets the activation increasing speed in accordance with the heat capacity of the exhaust system including the exhaust pipe. Therefore, the catalyst temperature can be quickly and effectively raised at the time of idling at the start of the engine, and the catalyst temperature rise control device for the internal combustion engine which can sufficiently satisfy the exhaust gas regulation can be obtained.

According to a nineteenth aspect of the present invention, in the twelfth aspect, the idle speed increasing means sets the target idle speed as about 100 rpm higher than the normal idle speed as the activation increased speed. Since the raised value is set, the catalyst temperature rise control device of the internal combustion engine that can quickly and effectively raise the catalyst temperature at the time of idling at the time of starting and that can sufficiently satisfy the exhaust gas regulation is provided. There is an effect that can be obtained.

According to a twentieth aspect of the present invention, in the twelfth aspect, the air-fuel ratio control means for controlling the air-fuel ratio of the internal combustion engine in accordance with the operating state, and when the catalyst temperature is lower than a predetermined temperature, The air-fuel ratio leaning means for setting the target air-fuel ratio of the internal combustion engine to an activated lean air-fuel ratio higher than the air-fuel ratio during normal control and higher than the stoichiometric air-fuel ratio is provided. A synergistic effect with the fuel-ratio lean correction enables a catalyst temperature rise control device for an internal combustion engine that can more quickly and effectively raise the catalyst temperature during idling at start-up and sufficiently satisfy exhaust gas regulations. Has the effect.

According to a twenty-first aspect of the present invention, in the twentieth aspect, the ignition timing control means for controlling the ignition timing of the internal combustion engine in accordance with the operating state, and when the catalyst temperature is lower than a predetermined temperature, An ignition timing retarding means for correcting the target ignition timing of the internal combustion engine to an activation retarded ignition timing that is more retarded than the ignition timing at the time of the normal control over the second predetermined period; The synergistic effect of the correction, the air-fuel ratio lean correction, and the ignition timing retard correction allows the catalyst temperature to be raised more quickly and effectively during idling at the time of starting, and the internal combustion to sufficiently satisfy exhaust gas regulations. There is an effect that a catalyst temperature rise control device of the engine can be obtained.

According to a twenty-second aspect of the present invention, in the twenty-first aspect, the ignition timing retarding means includes a first comparing means for comparing the catalyst temperature with a first predetermined temperature lower than the activation temperature, Second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the first predetermined temperature and corresponding to the activation temperature, and tailing for gradually changing the target ignition timing during target ignition timing switching control Means, when the catalyst temperature is equal to or higher than the first predetermined temperature, the tailing means gradually retards the target ignition timing by a constant value from the ignition timing during normal control to the activation retard ignition timing. The catalyst temperature is second
When the temperature is higher than the predetermined temperature, the target ignition timing is gradually advanced by a constant value from the activation retarded ignition timing to the ignition timing at the time of the normal control, so that the starting is performed without impairing drivability. At the time of idling, the catalyst temperature can be raised more quickly and effectively, and there is an effect that a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy the exhaust gas regulation is obtained.

According to a twenty-third aspect of the present invention, in the twenty-first aspect, the ignition timing retarding means varies at least one of the activation retarded ignition timing and the second predetermined period according to the catalyst temperature. Since the setting is made, the catalyst temperature can be raised more quickly and effectively at the time of idling at the time of starting, and the effect of obtaining the catalyst temperature rise control device of the internal combustion engine which can sufficiently satisfy the exhaust gas regulation can be obtained. is there.

According to a twenty-fourth aspect of the present invention, in the twenty-first aspect, the ignition timing retarding means intermittently corrects the target ignition timing to the retard side for a second predetermined period. Therefore, a catalyst temperature rise control device for an internal combustion engine that can more quickly and effectively raise the catalyst temperature during idling at startup without impairing the ignition timing control itself and that can sufficiently satisfy exhaust gas regulations. There is an effect that can be obtained.

According to a twenty-fifth aspect of the present invention, in the twelfth aspect, the ignition timing control means for controlling the ignition timing of the internal combustion engine in accordance with the operating state; The ignition timing retarding means for correcting the target ignition timing of the internal combustion engine to the retard side over the second predetermined period is provided. At the time of idling, the catalyst temperature can be raised more quickly and effectively, and there is an effect that a catalyst temperature rise control device for an internal combustion engine that can sufficiently satisfy exhaust gas regulations can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an air-fuel ratio control operation according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart specifically showing an air-fuel ratio leaning correction tailing process operation (step S3) according to the first embodiment of the present invention.

FIG. 3 is a flowchart specifically showing an air-fuel ratio normalization return tailing processing operation (step S5) according to the first embodiment of the present invention.

FIG. 4 is a timing chart for explaining an air-fuel ratio leaning correction operation according to Embodiment 1 of the present invention;

FIG. 5 is an explanatory diagram showing a change over time of the engine speed at the time of starting according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a time change of an air-fuel ratio at the time of starting according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a time change of the upstream-side catalyst temperature at the time of startup related to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a time change of the downstream catalyst temperature at the time of starting according to the first embodiment of the present invention.

FIG. 9 is a characteristic diagram illustrating a change in exhaust gas temperature with respect to an air-fuel ratio according to the first embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a change over time in a catalyst temperature according to the first embodiment of the present invention.

FIG. 11 is a characteristic diagram showing a change in an air-fuel ratio with respect to a cooling water temperature according to the first embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a time change of the air-fuel ratio immediately after the start during the normal control according to the first embodiment of the present invention.

FIG. 13 is a flowchart showing an operation for estimating and calculating a catalyst temperature according to Embodiment 2 of the present invention;

FIG. 14 is an explanatory diagram showing an estimated value of an initial catalyst temperature according to Embodiment 2 of the present invention.

FIG. 15 is an explanatory diagram showing a state of consumption of thermal energy (exhaust heat) of exhaust gas according to the second embodiment of the present invention.

FIG. 16 is a characteristic diagram showing the relationship between the amount of heat conduction to the exhaust system and the temperature rise of the exhaust system according to the second embodiment of the present invention.

FIG. 17 is a characteristic diagram showing a relationship between a heat conduction amount to an exhaust system and a thermal time constant of the exhaust system according to the second embodiment of the present invention.

FIG. 18 is a characteristic diagram showing the relationship between the amount of heat conduction to the catalyst and the temperature rise of the catalyst according to the second embodiment of the present invention.

FIG. 19 is a characteristic diagram showing a relationship between a heat conduction amount to a catalyst and a thermal time constant of the catalyst according to the second embodiment of the present invention.

FIG. 20 is an explanatory diagram showing an exhaust temperature estimation calculation operation according to Embodiment 3 of the present invention;

FIG. 21 is an explanatory diagram showing an air-fuel ratio setting processing operation according to Embodiment 3 of the present invention;

FIG. 22 is a flowchart showing a process for correcting an idle speed for promoting catalyst activation according to a catalyst temperature according to Embodiment 4 of the present invention;

FIG. 23 shows a tailing processing operation for correcting an increase in idle speed (step S3) according to the fourth embodiment of the present invention.
It is a flowchart which shows 3) concretely.

FIG. 24 is a tailing processing operation for returning to the normalization of the idle speed (step S3) according to the fourth embodiment of the present invention;
It is a flowchart which shows 5) specifically.

FIG. 25 shows a cooling water temperature according to Embodiment 4 of the present invention;
5 is a timing chart showing changes over time of an idle speed, a catalyst temperature, and a target idle speed during normal control.

FIG. 26 is a characteristic diagram showing a relationship between a target idle speed and a generated heat amount according to the fourth embodiment of the present invention.

FIG. 27 is a characteristic diagram showing a target idle speed set according to a cooling water temperature according to Embodiment 4 of the present invention.

FIG. 28 is an explanatory diagram showing a temporal change of a target idle speed immediately after starting during normal control according to Embodiment 4 of the present invention;

FIG. 29 is an explanatory diagram showing a control operation in which the idle rotation speed increase correction and the air-fuel ratio lean correction are combined according to the seventh embodiment of the present invention.

FIG. 30 is a flowchart showing a catalyst activation accelerating ignition timing correction process according to a catalyst temperature according to Embodiment 8 of the present invention.

FIG. 31 is a flowchart specifically showing a tailing processing operation (step S53) for ignition timing retard correction according to the eighth embodiment of the present invention.

FIG. 32 is a flowchart specifically showing a tailing process operation (step S55) for returning ignition timing to normalization according to the eighth embodiment of the present invention.

FIG. 33 is a characteristic diagram showing a change in target ignition timing with respect to cooling water temperature according to Embodiment 8 of the present invention.

FIG. 34 is a timing chart showing temporal changes in catalyst temperature and target ignition timing according to an eighth embodiment of the present invention.

FIG. 35 is an explanatory diagram showing a control operation in which an idle rotation speed increase correction, an air-fuel ratio lean correction, and an ignition timing retard correction are combined according to an eighth embodiment of the present invention.

FIG. 36 is a flowchart showing a control operation according to Embodiment 9 of the present invention.

FIG. 37 is a timing chart showing a control operation according to Embodiment 9 of the present invention.

FIG. 38 is a circuit configuration diagram showing a conventional catalyst temperature rise control device for an internal combustion engine.

FIG. 39 is an explanatory diagram showing a change in an exhaust gas purification rate with respect to a general catalyst temperature.

[Explanation of symbols]

1 engine, 2 intake pipe, 3 exhaust pipe, 5 air flow sensor, 6 throttle valve, 7 bypass passage, 8
ISC valve, 9 air-fuel ratio sensor, 10, 11 catalyst, 1
2 injector, 13 crank angle sensor, 14E
CU, A / F air-fuel ratio, A / FL activated lean air-fuel ratio,
A / Fn Normal control air-fuel ratio, A / Fo target air-fuel ratio, CISC control signal, CA crank angle signal, Ni
o Target idle speed, Nin idle speed during normal control, NiU activation rising speed, P ignition signal,
Qa Intake amount (load), Po target ignition timing, Pn normal control ignition timing, PR activation retard ignition timing, TA
s Start-up intake air temperature, TC catalyst temperature, TCs start-up catalyst temperature, TE exhaust system temperature, TEs start-up exhaust system temperature,
TH exhaust temperature, TW cooling water temperature, TWs starting water temperature, T1, T1a, T1b first predetermined temperature, T2, T
2a, T2b Second predetermined temperature, ΣQ, ΣQH Heat generation, ΔF1, ΔF2, ΔN1, ΔN2, ΔP1, ΔP2
Constant value, S3 Step of correcting target air-fuel ratio to lean side, S11, S12, S11A, S12A tailing processing step, S33 Step of correcting upward target idle speed, S41, S42, S41A, S42A
Tailing processing step, S53 step of retarding the target ignition timing, S61, S62, S61A, S6
2A tailing processing step.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02P 5/15 F02P 5/15 EF term (reference) 3G022 CA01 CA03 DA02 DA04 DA07 EA00 FA00 GA01 GA05 GA06 GA09 GA10 GA11 3G084 BA06 BA09 BA17 CA01 CA03 DA00 DA10 FA02 FA07 FA27 FA33 FA38 3G301 JA00 JA21 KA01 KA07 LA00 LA04 MA01 NA08 NB02 ND01 NE00 NE13 NE15 NE23 PA01Z PA10Z PD11Z PD12Z PE01A PE01Z PE03Z PE08Z

Claims (25)

[Claims] 1. A catalyst comprising a three-way converter provided in an exhaust pipe of an internal combustion engine, a catalyst temperature obtaining means for obtaining information corresponding to a temperature of the catalyst as a catalyst temperature, and an operating state of the internal combustion engine Various types of sensors that detect the temperature of the internal combustion engine, and an air-fuel ratio control unit that controls an air-fuel ratio of the internal combustion engine in accordance with the operating state. When the catalyst temperature is lower than a predetermined temperature corresponding to the activation temperature of the catalyst, the catalyst In order to promote the activation of, the air-fuel ratio leaning means for correcting the target air-fuel ratio of the internal combustion engine to the lean side, the various sensors, at least intake air amount information corresponding to the load of the internal combustion engine, Detecting crank angle information corresponding to the rotation speed of the internal combustion engine, the air-fuel ratio leaning means, when the catalyst temperature is lower than the predetermined temperature, the target air-fuel ratio, during normal control A catalyst temperature rise control device for an internal combustion engine, wherein an activation lean air-fuel ratio is set higher than an air-fuel ratio and higher than a stoichiometric air-fuel ratio. 2. The air-fuel ratio leaning means: first comparing means for comparing the catalyst temperature with a first predetermined temperature near the activation temperature; and A second comparing means for comparing the catalyst temperature with a second predetermined temperature higher than the second predetermined temperature corresponding to the activation temperature, wherein the catalyst temperature is within a range between the first predetermined temperature and the second predetermined temperature. The controller according to claim 1, wherein the target air-fuel ratio is set to the activated lean air-fuel ratio. 3. The air-fuel ratio leaning means includes a tailing means for gradually changing the target air-fuel ratio at the time of the target air-fuel ratio switching control, and the tailing means comprises: When the temperature is equal to or higher than a predetermined temperature, the target air-fuel ratio is gradually increased by a constant value from the air-fuel ratio during the normal control to the activated lean air-fuel ratio, and the catalyst temperature is higher than the second predetermined temperature. 3. The control system according to claim 2, wherein the target air-fuel ratio is gradually decreased by a constant value from the activated lean air-fuel ratio to the air-fuel ratio in the normal control. apparatus. 4. The control device according to claim 1, wherein the catalyst temperature acquisition means includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature. . 5. An exhaust gas temperature sensor provided in an exhaust pipe of the internal combustion engine for detecting an exhaust gas temperature; a catalyst temperature estimating device for estimating and calculating the catalyst temperature based on the exhaust gas temperature; The catalyst temperature rise control device for an internal combustion engine according to claim 1, comprising: 6. The internal combustion engine according to claim 1, wherein the catalyst temperature obtaining means includes a catalyst temperature estimating means for estimating and calculating the catalyst temperature based on at least intake air amount information of the internal combustion engine. Catalyst temperature rise control device. 7. The catalyst temperature estimating means includes initial temperature estimating means for estimating and calculating an initial temperature of the catalyst, wherein the initial temperature estimating means is based on at least a starting water temperature and a starting intake air temperature of the internal combustion engine. 7. The control device according to claim 6, wherein the initial temperature of the catalyst is estimated and calculated. 8. When the starting water temperature and the starting intake air temperature are substantially equal, the initial temperature estimating means estimates the starting water temperature as an initial temperature of the catalyst, and calculates the starting water temperature and the starting water temperature. 7. The catalyst for an internal combustion engine according to claim 6, wherein when the intake air temperature at startup is different, an initial temperature of the catalyst is estimated and calculated based on a difference between the water temperature at startup and the intake air temperature at startup. Heating control device. 9. The catalyst temperature estimating means sets a water temperature at the start of the internal combustion engine as an initial catalyst temperature, and calculates a generated heat amount calculated from the intake air amount information and a heat capacity of an exhaust system including the exhaust pipe. The catalyst temperature rise control device for an internal combustion engine according to claim 6, wherein the catalyst temperature is estimated and calculated based on the following equation. 10. The controller according to claim 1, wherein the predetermined temperature is set to a value obtained by adding a predetermined margin temperature to an activation temperature of the catalyst. 11. The controller according to claim 1, wherein the predetermined temperature is set to a value obtained by subtracting a predetermined margin temperature from an activation temperature of the catalyst. 12. A catalyst comprising a three-way converter provided in an exhaust pipe of an internal combustion engine, catalyst temperature obtaining means for obtaining information corresponding to the temperature of the catalyst as a catalyst temperature, and an operating state of the internal combustion engine Various kinds of sensors for detecting an idle speed of the internal combustion engine in accordance with the operating state; and when the catalyst temperature is lower than a predetermined temperature corresponding to an activation temperature of the catalyst, the catalyst Idle speed increasing means for correcting the target idle speed of the internal combustion engine to be higher than the idle speed at the time of normal control in order to promote activation of the internal combustion engine. When the catalyst temperature is lower than the predetermined temperature, the target idle speed is controlled during the normal control for a predetermined period until the catalyst temperature reaches the activation temperature. Catalyst Atsushi Nobori control apparatus for an internal combustion engine and sets a higher activation increased engine speed than idle speed. 13. An idle speed increasing means for comparing the catalyst temperature with a first predetermined temperature lower than the activation temperature, a first comparison means for comparing the catalyst temperature with the first predetermined temperature. Second comparing means for comparing with a second predetermined temperature that is high and corresponds to the activation temperature, wherein the catalyst temperature is in a range between the first predetermined temperature and the second predetermined temperature. 13. The controller according to claim 12, wherein the target idle rotation speed is set to the activation increase rotation speed. 14. The idle speed increasing means includes tailing means for gradually changing the target idle speed during the switching control of the target idle speed. If the temperature is equal to or higher than 1, the target idle speed is gradually increased by a constant value from the idle speed during the normal control to the activation rise speed, and the catalyst temperature is increased to the second predetermined speed. The internal combustion engine according to claim 13, wherein when the temperature is higher than the temperature, the target idle speed is gradually decreased by a constant value from the activation rising speed to the idle speed during the normal control. Engine catalyst temperature rise control device. 15. The control device according to claim 12, wherein the catalyst temperature acquisition means includes a temperature sensor provided on the catalyst for directly detecting the catalyst temperature. . 16. An exhaust gas temperature sensor provided in an exhaust pipe of the internal combustion engine for detecting an exhaust gas temperature, a catalyst temperature obtaining means for estimating and calculating the catalyst temperature based on the exhaust gas temperature, and The catalyst temperature rise control device for an internal combustion engine according to claim 12, comprising: 17. The catalyst temperature estimating means according to claim 12, wherein said catalyst temperature obtaining means includes a catalyst temperature estimating means for estimating and calculating said catalyst temperature based on at least information on a water temperature at start of said internal combustion engine and intake air amount information. A catalyst temperature rise control device for an internal combustion engine. 18. The catalyst for an internal combustion engine according to claim 12, wherein said idle speed increasing means sets said activation rising speed in accordance with a heat capacity of an exhaust system including said exhaust pipe. Heating control device. 19. The idle rotation speed increasing means sets, as the activation increase rotation speed, a value obtained by increasing the target idle rotation speed by about 100 rpm from a normal idle rotation speed. The catalyst temperature rise control device for an internal combustion engine according to claim 12. 20. An air-fuel ratio control means for controlling an air-fuel ratio of the internal combustion engine according to the operation state, and a normal control of a target air-fuel ratio of the internal combustion engine when the catalyst temperature is lower than the predetermined temperature. 13. A catalyst temperature raising control device for an internal combustion engine according to claim 12, further comprising: air-fuel ratio leaning means for setting an activated lean air-fuel ratio higher than the air-fuel ratio at the time and higher than the stoichiometric air-fuel ratio. . 21. An ignition timing control means for controlling an ignition timing of the internal combustion engine according to the operating state, and a target of the internal combustion engine for a second predetermined period when the catalyst temperature is lower than the predetermined temperature. 21. An internal combustion engine catalyst raising device according to claim 20, further comprising: ignition timing retarding means for correcting the ignition timing to an activation retarded ignition timing on the more retarded side of the ignition timing in the normal control. Temperature control device. 22. The ignition timing retarding means, first comparing means for comparing the catalyst temperature with a first predetermined temperature lower than the activation temperature, and wherein the catalyst temperature is lower than the first predetermined temperature. A second comparing means for comparing the target ignition timing with a second predetermined temperature that is high and corresponding to the activation temperature; and a tailing means for gradually changing the target ignition timing when the target ignition timing is switched. The means, when the catalyst temperature is equal to or higher than the first predetermined temperature, gradually retards the target ignition timing by a constant value from the ignition timing at the time of the normal control to the activation retard ignition timing, When the catalyst temperature is higher than the second predetermined temperature, the target ignition timing is gradually advanced by a constant value from the activation retard ignition timing to the ignition timing in the normal control. Claims 22. The catalyst temperature rise control device for an internal combustion engine according to 21. 23. The ignition timing retarding means according to claim 21, wherein at least one of the activation retarded ignition timing and the second predetermined period is variably set according to the catalyst temperature. A catalyst temperature rise control device for an internal combustion engine according to the above. 24. The catalyst for an internal combustion engine according to claim 21, wherein the ignition timing retarding means intermittently corrects the target ignition timing to a retard side over the second predetermined period. Heating control device. 25. An ignition timing control means for controlling an ignition timing of the internal combustion engine according to the operating state, and a target of the internal combustion engine for a second predetermined period when the catalyst temperature is lower than the predetermined temperature. 13. The catalyst temperature rise control device for an internal combustion engine according to claim 12, further comprising: ignition timing retarding means for correcting the ignition timing to a retard side.